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                                     350 BC
                                     TOPICS
                                  by Aristotle
                     translated by W. A. Pickard-Cambridge
                              Book I
                                 1

  OUR treatise proposes to find a line of inquiry whereby we shall
be able to reason from opinions that are generally accepted about
every problem propounded to us, and also shall ourselves, when
standing up to an argument, avoid saying anything that will obstruct
us. First, then, we must say what reasoning is, and what its varieties
are, in order to grasp dialectical reasoning: for this is the object
of our search in the treatise before us.
  Now reasoning is an argument in which, certain things being laid
down, something other than these necessarily comes about through them.
(a) It is a 'demonstration', when the premisses from which the
reasoning starts are true and primary, or are such that our
knowledge of them has originally come through premisses which are
primary and true: (b) reasoning, on the other hand, is
'dialectical', if it reasons from opinions that are generally
accepted. Things are 'true' and 'primary' which are believed on the
strength not of anything else but of themselves: for in regard to
the first principles of science it is improper to ask any further
for the why and wherefore of them; each of the first principles should
command belief in and by itself. On the other hand, those opinions are
'generally accepted' which are accepted by every one or by the
majority or by the philosophers-i.e. by all, or by the majority, or by
the most notable and illustrious of them. Again (c), reasoning is
'contentious' if it starts from opinions that seem to be generally
accepted, but are not really such, or again if it merely seems to
reason from opinions that are or seem to be generally accepted. For
not every opinion that seems to be generally accepted actually is
generally accepted. For in none of the opinions which we call
generally accepted is the illusion entirely on the surface, as happens
in the case of the principles of contentious arguments; for the nature
of the fallacy in these is obvious immediately, and as a rule even
to persons with little power of comprehension. So then, of the
contentious reasonings mentioned, the former really deserves to be
called 'reasoning' as well, but the other should be called
'contentious reasoning', but not 'reasoning', since it appears to
reason, but does not really do so. Further (d), besides all the
reasonings we have mentioned there are the mis-reasonings that start
from the premisses peculiar to the special sciences, as happens (for
example) in the case of geometry and her sister sciences. For this
form of reasoning appears to differ from the reasonings mentioned
above; the man who draws a false figure reasons from things that are
neither true and primary, nor yet generally accepted. For he does
not fall within the definition; he does not assume opinions that are
received either by every one or by the majority or by
philosophers-that is to say, by all, or by most, or by the most
illustrious of them-but he conducts his reasoning upon assumptions
which, though appropriate to the science in question, are not true;
for he effects his mis-reasoning either by describing the
semicircles wrongly or by drawing certain lines in a way in which they
could not be drawn.
  The foregoing must stand for an outline survey of the species of
reasoning. In general, in regard both to all that we have already
discussed and to those which we shall discuss later, we may remark
that that amount of distinction between them may serve, because it
is not our purpose to give the exact definition of any of them; we
merely want to describe them in outline; we consider it quite enough
from the point of view of the line of inquiry before us to be able
to recognize each of them in some sort of way.

                                 2

  Next in order after the foregoing, we must say for how many and
for what purposes the treatise is useful. They are
three-intellectual training, casual encounters, and the
philosophical sciences. That it is useful as a training is obvious
on the face of it. The possession of a plan of inquiry will enable
us more easily to argue about the subject proposed. For purposes of
casual encounters, it is useful because when we have counted up the
opinions held by most people, we shall meet them on the ground not
of other people's convictions but of their own, while we shift the
ground of any argument that they appear to us to state unsoundly.
For the study of the philosophical sciences it is useful, because
the ability to raise searching difficulties on both sides of a subject
will make us detect more easily the truth and error about the
several points that arise. It has a further use in relation to the
ultimate bases of the principles used in the several sciences. For
it is impossible to discuss them at all from the principles proper
to the particular science in hand, seeing that the principles are
the prius of everything else: it is through the opinions generally
held on the particular points that these have to be discussed, and
this task belongs properly, or most appropriately, to dialectic: for
dialectic is a process of criticism wherein lies the path to the
principles of all inquiries.

                                 3

  We shall be in perfect possession of the way to proceed when we
are in a position like that which we occupy in regard to rhetoric
and medicine and faculties of that kind: this means the doing of
that which we choose with the materials that are available. For it
is not every method that the rhetorician will employ to persuade, or
the doctor to heal; still, if he omits none of the available means, we
shall say that his grasp of the science is adequate.

                                 4

  First, then, we must see of what parts our inquiry consists. Now
if we were to grasp (a) with reference to how many, and what kind
of, things arguments take place, and with what materials they start,
and (h) how we are to become well supplied with these, we should
have sufficiently won our goal. Now the materials with which arguments
start are equal in number, and are identical, with the subjects on
which reasonings take place. For arguments start with
'propositions', while the subjects on which reasonings take place
are 'problems'. Now every proposition and every problem indicates
either a genus or a peculiarity or an accident-for the differentia
too, applying as it does to a class (or genus), should be ranked
together with the genus. Since, however, of what is peculiar to
anything part signifies its essence, while part does not, let us
divide the 'peculiar' into both the aforesaid parts, and call that
part which indicates the essence a 'definition', while of the
remainder let us adopt the terminology which is generally current
about these things, and speak of it as a 'property'. What we have
said, then, makes it clear that according to our present division, the
elements turn out to be four, all told, namely either property or
definition or genus or accident. Do not let any one suppose us to mean
that each of these enunciated by itself constitutes a proposition or
problem, but only that it is from these that both problems and
propositions are formed. The difference between a problem and a
proposition is a difference in the turn of the phrase. For if it be
put in this way, "'An animal that walks on two feet" is the definition
of man, is it not?' or '"Animal" is the genus of man, is it not?'
the result is a proposition: but if thus, 'Is "an animal that walks on
two feet" a definition of man or no?' [or 'Is "animal" his genus or
no?'] the result is a problem. Similarly too in other cases.
Naturally, then, problems and propositions are equal in number: for
out of every proposition you will make a problem if you change the
turn of the phrase.

                                 5

  We must now say what are 'definition', 'property', 'genus', and
'accident'. A 'definition' is a phrase signifying a thing's essence.
It is rendered in the form either of a phrase in lieu of a term, or of
a phrase in lieu of another phrase; for it is sometimes possible to
define the meaning of a phrase as well. People whose rendering
consists of a term only, try it as they may, clearly do not render the
definition of the thing in question, because a definition is always
a phrase of a certain kind. One may, however, use the word
'definitory' also of such a remark as 'The "becoming" is "beautiful"',
and likewise also of the question, 'Are sensation and knowledge the
same or different?', for argument about definitions is mostly
concerned with questions of sameness and difference. In a word we
may call 'definitory' everything that falls under the same branch of
inquiry as definitions; and that all the above-mentioned examples
are of this character is clear on the face of them. For if we are able
to argue that two things are the same or are different, we shall be
well supplied by the same turn of argument with lines of attack upon
their definitions as well: for when we have shown that they are not
the same we shall have demolished the definition. Observe, please,
that the converse of this last statement does not hold: for to show
that they are the same is not enough to establish a definition. To
show, however, that they are not the same is enough of itself to
overthrow it.
  A 'property' is a predicate which does not indicate the essence of a
thing, but yet belongs to that thing alone, and is predicated
convertibly of it. Thus it is a property of man to-be-capable of
learning grammar: for if A be a man, then he is capable of learning
grammar, and if he be capable of learning grammar, he is a man. For no
one calls anything a 'property' which may possibly belong to something
else, e.g. 'sleep' in the case of man, even though at a certain time
it may happen to belong to him alone. That is to say, if any such
thing were actually to be called a property, it will be called not a
'property' absolutely, but a 'temporary' or a 'relative' property: for
'being on the right hand side' is a temporary property, while
'two-footed' is in point of fact ascribed as a property in certain
relations; e.g. it is a property of man relatively to a horse and a
dog. That nothing which may belong to anything else than A is a
convertible predicate of A is clear: for it does not necessarily
follow that if something is asleep it is a man.
  A 'genus' is what is predicated in the category of essence of a
number of things exhibiting differences in kind. We should treat as
predicates in the category of essence all such things as it would be
appropriate to mention in reply to the question, 'What is the object
before you?'; as, for example, in the case of man, if asked that
question, it is appropriate to say 'He is an animal'. The question,
'Is one thing in the same genus as another or in a different one?'
is also a 'generic' question; for a question of that kind as well
falls under the same branch of inquiry as the genus: for having argued
that 'animal' is the genus of man, and likewise also of ox, we shall
have argued that they are in the same genus; whereas if we show that
it is the genus of the one but not of the other, we shall have
argued that these things are not in the same genus.
  An 'accident' is (i) something which, though it is none of the
foregoing-i.e. neither a definition nor a property nor a genus yet
belongs to the thing: (something which may possibly either belong or
not belong to any one and the self-same thing, as (e.g.) the
'sitting posture' may belong or not belong to some self-same thing.
Likewise also 'whiteness', for there is nothing to prevent the same
thing being at one time white, and at another not white. Of the
definitions of accident the second is the better: for if he adopts the
first, any one is bound, if he is to understand it, to know already
what 'definition' and 'genus' and 'property' are, whereas the second
is sufficient of itself to tell us the essential meaning of the term
in question. To Accident are to be attached also all comparisons of
things together, when expressed in language that is drawn in any
kind of way from what happens (accidit) to be true of them; such as,
for example, the question, 'Is the honourable or the expedient
preferable?' and 'Is the life of virtue or the life of self-indulgence
the pleasanter?', and any other problem which may happen to be phrased
in terms like these. For in all such cases the question is 'to which
of the two does the predicate in question happen (accidit) to belong
more closely?' It is clear on the face of it that there is nothing
to prevent an accident from becoming a temporary or relative property.
Thus the sitting posture is an accident, but will be a temporary
property, whenever a man is the only person sitting, while if he be
not the only one sitting, it is still a property relatively to those
who are not sitting. So then, there is nothing to prevent an
accident from becoming both a relative and a temporary property; but a
property absolutely it will never be.

                                 6

  We must not fail to observe that all remarks made in criticism of
a 'property' and 'genus' and 'accident' will be applicable to
'definitions' as well. For when we have shown that the attribute in
question fails to belong only to the term defined, as we do also in
the case of a property, or that the genus rendered in the definition
is not the true genus, or that any of the things mentioned in the
phrase used does not belong, as would be remarked also in the case
of an accident, we shall have demolished the definition; so that, to
use the phrase previously employed,' all the points we have enumerated
might in a certain sense be called 'definitory'. But we must not on
this account expect to find a single line of inquiry which will
apply universally to them all: for this is not an easy thing to
find, and, even were one found, it would be very obscure indeed, and
of little service for the treatise before us. Rather, a special plan
of inquiry must be laid down for each of the classes we have
distinguished, and then, starting from the rules that are
appropriate in each case, it will probably be easier to make our way
right through the task before us. So then, as was said before,' we
must outline a division of our subject, and other questions we must
relegate each to the particular branch to which it most naturally
belongs, speaking of them as 'definitory' and 'generic' questions. The
questions I mean have practically been already assigned to their
several branches.

                                 7

  First of all we must define the number of senses borne by the term
'Sameness'. Sameness would be generally regarded as falling, roughly
speaking, into three divisions. We generally apply the term
numerically or specifically or generically-numerically in cases
where there is more than one name but only one thing, e.g. 'doublet'
and 'cloak'; specifically, where there is more than one thing, but
they present no differences in respect of their species, as one man
and another, or one horse and another: for things like this that
fall under the same species are said to be 'specifically the same'.
Similarly, too, those things are called generically the same which
fall under the same genus, such as a horse and a man. It might
appear that the sense in which water from the same spring is called
'the same water' is somehow different and unlike the senses
mentioned above: but really such a case as this ought to be ranked
in the same class with the things that in one way or another are
called 'the same' in view of unity of species. For all such things
seem to be of one family and to resemble one another. For the reaon
why all water is said to be specifically the same as all other water
is because of a certain likeness it bears to it, and the only
difference in the case of water drawn from the same spring is this,
that the likeness is more emphatic: that is why we do not
distinguish it from the things that in one way or another are called
'the same' in view of unity of species. It is generally supposed
that the term 'the same' is most used in a sense agreed on by every
one when applied to what is numerically one. But even so, it is apt to
be rendered in more than one sense; its most literal and primary use
is found whenever the sameness is rendered in reference to an
alternative name or definition, as when a cloak is said to be the same
as a doublet, or an animal that walks on two feet is said to be the
same as a man: a second sense is when it is rendered in reference to a
property, as when what can acquire knowledge is called the same as a
man, and what naturally travels upward the same as fire: while a third
use is found when it is rendered in reference to some term drawn
from Accident, as when the creature who is sitting, or who is musical,
is called the same as Socrates. For all these uses mean to signify
numerical unity. That what I have just said is true may be best seen
where one form of appellation is substituted for another. For often
when we give the order to call one of the people who are sitting down,
indicating him by name, we change our description, whenever the person
to whom we give the order happens not to understand us; he will, we
think, understand better from some accidental feature; so we bid him
call to us 'the man who is sitting' or 'who is conversing over
there'-clearly supposing ourselves to be indicating the same object by
its name and by its accident.

                                 8

  Of 'sameness' then, as has been said,' three senses are to be
distinguished. Now one way to confirm that the elements mentioned
above are those out of which and through which and to which
arguments proceed, is by induction: for if any one were to survey
propositions and problems one by one, it would be seen that each was
formed either from the definition of something or from its property or
from its genus or from its accident. Another way to confirm it is
through reasoning. For every predicate of a subject must of
necessity be either convertible with its subject or not: and if it
is convertible, it would be its definition or property, for if it
signifies the essence, it is the definition; if not, it is a property:
for this was what a property is, viz. what is predicated
convertibly, but does not signify the essence. If, on the other
hand, it is not predicated convertibly of the thing, it either is or
is not one of the terms contained in the definition of the subject:
and if it be one of those terms, then it will be the genus or the
differentia, inasmuch as the definition consists of genus and
differentiae; whereas, if it be not one of those terms, clearly it
would be an accident, for accident was said' to be what belongs as
an attribute to a subject without being either its definition or its
genus or a property.

                                 9

  Next, then, we must distinguish between the classes of predicates in
which the four orders in question are found. These are ten in
number: Essence, Quantity, Quality, Relation, Place, Time, Position,
State, Activity, Passivity. For the accident and genus and property
and definition of anything will always be in one of these
categories: for all the propositions found through these signify
either something's essence or its quality or quantity or some one of
the other types of predicate. It is clear, too, on the face of it that
the man who signifies something's essence signifies sometimes a
substance, sometimes a quality, sometimes some one of the other
types of predicate. For when man is set before him and he says that
what is set there is 'a man' or 'an animal', he states its essence and
signifies a substance; but when a white colour is set before him and
he says that what is set there is 'white' or is 'a colour', he
states its essence and signifies a quality. Likewise, also, if a
magnitude of a cubit be set before him and he says that what is set
there is a magnitude of a cubit, he will be describing its essence and
signifying a quantity. Likewise, also, in the other cases: for each of
these kinds of predicate, if either it be asserted of itself, or its
genus be asserted of it, signifies an essence: if, on the other
hand, one kind of predicate is asserted of another kind, it does not
signify an essence, but a quantity or a quality or one of the other
kinds of predicate. Such, then, and so many, are the subjects on which
arguments take place, and the materials with which they start. How
we are to acquire them, and by what means we are to become well
supplied with them, falls next to be told.

                                10

  First, then, a definition must be given of a 'dialectical
proposition' and a 'dialectical problem'. For it is not every
proposition nor yet every problem that is to be set down as
dialectical: for no one in his senses would make a proposition of what
no one holds, nor yet make a problem of what is obvious to everybody
or to most people: for the latter admits of no doubt, while to the
former no one would assent. Now a dialectical proposition consists
in asking something that is held by all men or by most men or by the
philosophers, i.e. either by all, or by most, or by the most notable
of these, provided it be not contrary to the general opinion; for a
man would probably assent to the view of the philosophers, if it be
not contrary to the opinions of most men. Dialectical propositions
also include views which are like those generally accepted; also
propositions which contradict the contraries of opinions that are
taken to be generally accepted, and also all opinions that are in
accordance with the recognized arts. Thus, supposing it to be a
general opinion that the knowledge of contraries is the same, it might
probably pass for a general opinion also that the perception of
contraries is the same: also, supposing it to be a general opinion
that there is but one single science of grammar, it might pass for a
general opinion that there is but one science of flute-playing as
well, whereas, if it be a general opinion that there is more than
one science of grammar, it might pass for a general opinion that there
is more than one science of flute-playing as well: for all these
seem to be alike and akin. Likewise, also, propositions
contradicting the contraries of general opinions will pass as
general opinions: for if it be a general opinion that one ought to
do good to one's friends, it will also be a general opinion that one
ought not to do them harm. Here, that one ought to do harm to one's
friends is contrary to the general view, and that one ought not to
do them harm is the contradictory of that contrary. Likewise also,
if one ought to do good to one's friends, one ought not to do good
to one's enemies: this too is the contradictory of the view contrary
to the general view; the contrary being that one ought to do good to
one's enemies. Likewise, also, in other cases. Also, on comparison, it
will look like a general opinion that the contrary predicate belongs
to the contrary subject: e.g. if one ought to do good to one's
friends, one ought also to do evil to one's enemies. it might appear
also as if doing good to one's friends were a contrary to doing evil
to one's enemies: but whether this is or is not so in reality as
well will be stated in the course of the discussion upon contraries.
Clearly also, all opinions that are in accordance with the arts are
dialectical propositions; for people are likely to assent to the views
held by those who have made a study of these things, e.g. on a
question of medicine they will agree with the doctor, and on a
question of geometry with the geometrician; and likewise also in other
cases.

                                11

  A dialectical problem is a subject of inquiry that contributes
either to choice and avoidance, or to truth and knowledge, and that
either by itself, or as a help to the solution of some other such
problem. It must, moreover, be something on which either people hold
no opinion either way, or the masses hold a contrary opinion to the
philosophers, or the philosophers to the masses, or each of them among
themselves. For some problems it is useful to know with a view to
choice or avoidance, e.g. whether pleasure is to be chosen or not,
while some it is useful to know merely with a view to knowledge,
e.g. whether the universe is eternal or not: others, again, are not
useful in and by themselves for either of these purposes, but yet help
us in regard to some such problems; for there are many things which we
do not wish to know in and by themselves, but for the sake of other
things, in order that through them we may come to know something else.
Problems also include questions in regard to which reasonings conflict
(the difficulty then being whether so-and so is so or not, there being
convincing arguments for both views); others also in regard to which
we have no argument because they are so vast, and we find it difficult
to give our reasons, e.g. the question whether the universe is eternal
or no: for into questions of that kind too it is possible to inquire.
  Problems, then, and propositions are to be defined as aforesaid. A
'thesis' is a supposition of some eminent philosopher that conflicts
with the general opinion; e.g. the view that contradiction is
impossible, as Antisthenes said; or the view of Heraclitus that all
things are in motion; or that Being is one, as Melissus says: for to
take notice when any ordinary person expresses views contrary to men's
usual opinions would be silly. Or it may be a view about which we have
a reasoned theory contrary to men's usual opinions, e.g. the view
maintained by the sophists that what is need not in every case
either have come to be or be eternal: for a musician who is a
grammarian 'is' so without ever having 'come to be' so, or being so
eternally. For even if a man does not accept this view, he might do so
on the ground that it is reasonable.
  Now a 'thesis' also is a problem, though a problem is not always a
thesis, inasmuch as some problems are such that we have no opinion
about them either way. That a thesis, however, also forms a problem,
is clear: for it follows of necessity from what has been said that
either the mass of men disagree with the philosophers about the
thesis, or that the one or the other class disagree among
themselves, seeing that the thesis is a supposition in conflict with
general opinion. Practically all dialectical problems indeed are now
called 'theses'. But it should make no difference whichever
description is used; for our object in thus distinguishing them has
not been to create a terminology, but to recognize what differences
happen to be found between them.
  Not every problem, nor every thesis, should be examined, but only
one which might puzzle one of those who need argument, not
punishment or perception. For people who are puzzled to know whether
one ought to honour the gods and love one's parents or not need
punishment, while those who are puzzled to know whether snow is
white or not need perception. The subjects should not border too
closely upon the sphere of demonstration, nor yet be too far removed
from it: for the former cases admit of no doubt, while the latter
involve difficulties too great for the art of the trainer.

                                12

  Having drawn these definitions, we must distinguish how many species
there are of dialectical arguments. There is on the one hand
Induction, on the other Reasoning. Now what reasoning is has been said
before: induction is a passage from individuals to universals, e.g.
the argument that supposing the skilled pilot is the most effective,
and likewise the skilled charioteer, then in general the skilled man
is the best at his particular task. Induction is the more convincing
and clear: it is more readily learnt by the use of the senses, and
is applicable generally to the mass of men, though reasoning is more
forcible and effective against contradictious people.

                                13

  The classes, then, of things about which, and of things out of
which, arguments are constructed, are to be distinguished in the way
we have said before. The means whereby we are to become well
supplied with reasonings are four: (1) the securing of propositions;
(2) the power to distinguish in how many senses particular
expression is used; (3) the discovery of the differences of things;
(4) the investigation of likeness. The last three, as well, are in a
certain sense propositions: for it is possible to make a proposition
corresponding to each of them, e.g. (1) 'The desirable may mean either
the honourable or the pleasant or the expedient'; and (2) Sensation
differs from knowledge in that the latter may be recovered again after
it has been lost, while the former cannot'; and (3) The relation of
the healthy to health is like that of the vigorous to vigour'. The
first proposition depends upon the use of one term in several
senses, the second upon the differences of things, the third upon
their likenesses.

                                14

  Propositions should be selected in a number of ways corresponding to
the number of distinctions drawn in regard to the proposition: thus
one may first take in hand the opinions held by all or by most men
or by the philosophers, i.e. by all, or most, or the most notable of
them; or opinions contrary to those that seem to be generally held;
and, again, all opinions that are in accordance with the arts. We must
make propositions also of the contradictories of opinions contrary
to those that seem to be generally held, as was laid down before. It
is useful also to make them by selecting not only those opinions
that actually are accepted, but also those that are like these, e.g.
'The perception of contraries is the same'-the knowledge of them being
so-and 'we see by admission of something into ourselves, not by an
emission'; for so it is, too, in the case of the other senses; for
in hearing we admit something into ourselves; we do not emit; and we
taste in the same way. Likewise also in the other cases. Moreover, all
statements that seem to be true in all or in most cases, should be
taken as a principle or accepted position; for they are posited by
those who do not also see what exception there may be. We should
select also from the written handbooks of argument, and should draw up
sketch-lists of them upon each several kind of subject, putting them
down under separate headings, e.g. 'On Good', or 'On Life'-and that
'On Good' should deal with every form of good, beginning with the
category of essence. In the margin, too, one should indicate also
the opinions of individual thinkers, e.g. 'Empedocles said that the
elements of bodies were four': for any one might assent to the
saying of some generally accepted authority.
  Of propositions and problems there are-to comprehend the matter in
outline-three divisions: for some are ethical propositions, some are
on natural philosophy, while some are logical. Propositions such as
the following are ethical, e.g. 'Ought one rather to obey one's
parents or the laws, if they disagree?'; such as this are logical,
e.g. 'Is the knowledge of opposites the same or not?'; while such as
this are on natural philosophy, e.g. 'Is the universe eternal or not?'
Likewise also with problems. The nature of each of the aforesaid kinds
of proposition is not easily rendered in a definition, but we have
to try to recognize each of them by means of the familiarity
attained through induction, examining them in the light of the
illustrations given above.
  For purposes of philosophy we must treat of these things according
to their truth, but for dialectic only with an eye to general opinion.
All propositions should be taken in their most universal form; then,
the one should be made into many. E.g. 'The knowledge of opposites
is the same'; next, 'The knowledge of contraries is the same', and
that 'of relative terms'. In the same way these two should again be
divided, as long as division is possible, e.g. the knowledge of
'good and evil', of 'white and black', or 'cold and hot'. Likewise
also in other cases.

                                15

  On the formation, then, of propositions, the above remarks are
enough. As regards the number of senses a term bears, we must not only
treat of those terms which bear different senses, but we must also try
to render their definitions; e.g. we must not merely say that
justice and courage are called 'good' in one sense, and that what
conduces to vigour and what conduces to health are called so in
another, but also that the former are so called because of a certain
intrinsic quality they themselves have, the latter because they are
productive of a certain result and not because of any intrinsic
quality in themselves. Similarly also in other cases.
  Whether a term bears a number of specific meanings or one only,
may be considered by the following means. First, look and see if its
contrary bears a number of meanings, whether the discrepancy between
them be one of kind or one of names. For in some cases a difference is
at once displayed even in the names; e.g. the contrary of 'sharp' in
the case of a note is 'flat', while in the case of a solid edge it
is 'dull'. Clearly, then, the contrary of 'sharp' bears several
meanings, and if so, also does 'sharp'; for corresponding to each of
the former terms the meaning of its contrary will be different. For
'sharp' will not be the same when contrary to 'dull' and to 'flat',
though 'sharp' is the contrary of each. Again Barhu ('flat',
'heavy') in the case of a note has 'sharp' as its contrary, but in the
case of a solid mass 'light', so that Barhu is used with a number of
meanings, inasmuch as its contrary also is so used. Likewise, also,
'fine' as applied to a picture has 'ugly' as its contrary, but, as
applied to a house, 'ramshackle'; so that 'fine' is an ambiguous term.
  In some cases there is no discrepancy of any sort in the names used,
but a difference of kind between the meanings is at once obvious: e.g.
in the case of 'clear' and 'obscure': for sound is called 'clear'
and 'obscure', just as 'colour' is too. As regards the names, then,
there is no discrepancy, but the difference in kind between the
meanings is at once obvious: for colour is not called 'clear' in a
like sense to sound. This is plain also through sensation: for of
things that are the same in kind we have the same sensation, whereas
we do not judge clearness by the same sensation in the case of sound
and of colour, but in the latter case we judge by sight, in the former
by hearing. Likewise also with 'sharp' and 'dull' in regard to
flavours and solid edges: here in the latter case we judge by touch,
but in the former by taste. For here again there is no discrepancy
in the names used, in the case either of the original terms or of
their contraries: for the contrary also of sharp in either sense is
'dull'.
  Moreover, see if one sense of a term has a contrary, while another
has absolutely none; e.g. the pleasure of drinking has a contrary in
the pain of thirst, whereas the pleasure of seeing that the diagonal
is incommensurate with the side has none, so that 'pleasure' is used
in more than one sense. To 'love' also, used of the frame of mind, has
to 'hate' as its contrary, while as used of the physical activity
(kissing) it has none: clearly, therefore, to 'love' is an ambiguous
term. Further, see in regard to their intermediates, if some
meanings and their contraries have an intermediate, others have
none, or if both have one but not the same one, e.g. 'clear' and
'obscure' in the case of colours have 'grey' as an intermediate,
whereas in the case of sound they have none, or, if they have, it is
'harsh', as some people say that a harsh sound is intermediate.
'Clear', then, is an ambiguous term, and likewise also 'obscure'. See,
moreover, if some of them have more than one intermediate, while
others have but one, as is the case with 'clear' and 'obscure', for in
the case of colours there are numbers of intermediates, whereas in
regard to sound there is but one, viz. 'harsh'.
  Again, in the case of the contradictory opposite, look and see if it
bears more than one meaning. For if this bears more than one
meaning, then the opposite of it also will be used in more than one
meaning; e.g. 'to fail to see' a phrase with more than one meaning,
viz. (1) to fail to possess the power of sight, (2) to fail to put
that power to active use. But if this has more than one meaning, it
follows necessarily that 'to see' also has more than one meaning:
for there will be an opposite to each sense of 'to fail to see';
e.g. the opposite of 'not to possess the power of sight' is to possess
it, while of 'not to put the power of sight to active use', the
opposite is to put it to active use.
  Moreover, examine the case of terms that denote the privation or
presence of a certain state: for if the one term bears more than one
meaning, then so will the remaining term: e.g. if 'to have sense' be
used with more than one meaning, as applied to the soul and to the
body, then 'to be wanting in sense' too will be used with more than
one meaning, as applied to the soul and to the body. That the
opposition between the terms now in question depends upon the
privation or presence of a certain state is clear, since animals
naturally possess each kind of 'sense', both as applied to the soul
and as applied to the body.
  Moreover, examine the inflected forms. For if 'justly' has more than
one meaning, then 'just', also, will be used with more than one
meaning; for there will be a meaning of 'just' to each of the meanings
of 'justly'; e.g. if the word 'justly' be used of judging according to
one's own opinion, and also of judging as one ought, then 'just'
also will be used in like manner. In the same way also, if 'healthy'
has more than one meaning, then 'healthily' also will be used with
more than one meaning: e.g. if 'healthy' describes both what
produces health and what preserves health and what betokens health,
then 'healthily' also will be used to mean 'in such a way as to
produce' or 'preserve' or 'betoken' health. Likewise also in other
cases, whenever the original term bears more than one meaning, the
inflexion also that is formed from it will be used with more than
one meaning, and vice versa.
  Look also at the classes of the predicates signified by the term,
and see if they are the same in all cases. For if they are not the
same, then clearly the term is ambiguous: e.g. 'good' in the case of
food means 'productive of pleasure', and in the case of medicine
'productive of health', whereas as applied to the soul it means to
be of a certain quality, e.g. temperate or courageous or just: and
likewise also, as applied to 'man'. Sometimes it signifies what
happens at a certain time, as (e.g.) the good that happens at the
right time: for what happens at the right time is called good. Often
it signifies what is of certain quantity, e.g. as applied to the
proper amount: for the proper amount too is called good. So then the
term 'good' is ambiguous. In the same way also 'clear', as applied
to a body, signifies a colour, but in regard to a note it denotes what
is 'easy to hear'. 'Sharp', too, is in a closely similar case: for the
same term does not bear the same meaning in all its applications:
for a sharp note is a swift note, as the mathematical theorists of
harmony tell us, whereas a sharp (acute) angle is one that is less
than a right angle, while a sharp dagger is one containing a sharp
angle (point).
  Look also at the genera of the objects denoted by the same term, and
see if they are different without being subaltern, as (e.g.) 'donkey',
which denotes both the animal and the engine. For the definition of
them that corresponds to the name is different: for the one will be
declared to be an animal of a certain kind, and the other to be an
engine of a certain kind. If, however, the genera be subaltern,
there is no necessity for the definitions to be different. Thus (e.g.)
'animal' is the genus of 'raven', and so is 'bird'. Whenever therefore
we say that the raven is a bird, we also say that it is a certain kind
of animal, so that both the genera are predicated of it. Likewise also
whenever we call the raven a 'flying biped animal', we declare it to
be a bird: in this way, then, as well, both the genera are
predicated of raven, and also their definition. But in the case of
genera that are not subaltern this does not happen, for whenever we
call a thing an 'engine', we do not call it an animal, nor vice versa.
  Look also and see not only if the genera of the term before you
are different without being subaltern, but also in the case of its
contrary: for if its contrary bears several senses, clearly the term
before you does so as well.
  It is useful also to look at the definition that arises from the use
of the term in combination, e.g. of a 'clear (lit. white) body' of a
'clear note'. For then if what is peculiar in each case be abstracted,
the same expression ought to remain over. This does not happen in
the case of ambiguous terms, e.g. in the cases just mentioned. For the
former will be body possessing such and such a colour', while the
latter will be 'a note easy to hear'. Abstract, then, 'a body 'and'
a note', and the remainder in each case is not the same. It should,
however, have been had the meaning of 'clear' in each case been
synonymous.
  Often in the actual definitions as well ambiguity creeps in
unawares, and for this reason the definitions also should be examined.
If (e.g.) any one describes what betokens and what produces health
as 'related commensurably to health', we must not desist but go on
to examine in what sense he has used the term 'commensurably' in
each case, e.g. if in the latter case it means that 'it is of the
right amount to produce health', whereas in the for it means that
'it is such as to betoken what kind of state prevails'.
  Moreover, see if the terms cannot be compared as 'more or less' or
as 'in like manner', as is the case (e.g.) with a 'clear' (lit. white)
sound and a 'clear' garment, and a 'sharp' flavour and a 'sharp' note.
For neither are these things said to be clear or sharp 'in a like
degree', nor yet is the one said to be clearer or sharper than the
other. 'Clear', then, and 'sharp' are ambiguous. For synonyms are
always comparable; for they will always be used either in like manner,
or else in a greater degree in one case.
  Now since of genera that are different without being subaltern the
differentiae also are different in kind, e.g. those of 'animal' and
'knowledge' (for the differentiae of these are different), look and
see if the meanings comprised under the same term are differentiae
of genera that are different without being subaltern, as e.g.
'sharp' is of a 'note' and a 'solid'. For being 'sharp' differentiates
note from note, and likewise also one solid from another. 'Sharp',
then, is an ambiguous term: for it forms differentiae of genera that
are different without being subaltern.
  Again, see if the actual meanings included under the same term
themselves have different differentiae, e.g. 'colour' in bodies and
'colour' in tunes: for the differentiae of 'colour' in bodies are
'sight-piercing' and 'sight compressing', whereas 'colour' in melodies
has not the same differentiae. Colour, then, is an ambiguous term; for
things that are the same have the same differentiae.
  Moreover, since the species is never the differentia of anything,
look and see if one of the meanings included under the same term be
a species and another a differentia, as (e.g.) clear' (lit. white)
as applied to a body is a species of colour, whereas in the case of
a note it is a differentia; for one note is differentiated from
another by being 'clear'.

                                16

  The presence, then, of a number of meanings in a term may be
investigated by these and like means. The differences which things
present to each other should be examined within the same genera,
e.g. 'Wherein does justice differ from courage, and wisdom from
temperance?'-for all these belong to the same genus; and also from one
genus to another, provided they be not very much too far apart, e.g.
'Wherein does sensation differ from knowledge?: for in the case of
genera that are very far apart, the differences are entirely obvious.

                                17

  Likeness should be studied, first, in the case of things belonging
to different genera, the formulae being 'A:B = C:D' (e.g. as knowledge
stands to the object of knowledge, so is sensation related to the
object of sensation), and 'As A is in B, so is C in D' (e.g. as
sight is in the eye, so is reason in the soul, and as is a calm in the
sea, so is windlessness in the air). Practice is more especially
needed in regard to terms that are far apart; for in the case of the
rest, we shall be more easily able to see in one glance the points
of likeness. We should also look at things which belong to the same
genus, to see if any identical attribute belongs to them all, e.g.
to a man and a horse and a dog; for in so far as they have any
identical attribute, in so far they are alike.

                                18

  It is useful to have examined the number of meanings of a term
both for clearness' sake (for a man is more likely to know what it
is he asserts, if it bas been made clear to him how many meanings it
may have), and also with a view to ensuring that our reasonings
shall be in accordance with the actual facts and not addressed
merely to the term used. For as long as it is not clear in how many
senses a term is used, it is possible that the answerer and the
questioner are not directing their minds upon the same thing:
whereas when once it has been made clear how many meanings there
are, and also upon which of them the former directs his mind when he
makes his assertion, the questioner would then look ridiculous if he
failed to address his argument to this. It helps us also both to avoid
being misled and to mislead by false reasoning: for if we know the
number of meanings of a term, we shall certainly never be misled by
false reasoning, but shall know if the questioner fails to address his
argument to the same point; and when we ourselves put the questions we
shall be able to mislead him, if our answerer happens not to know
the number of meanings of our terms. This, however, is not possible in
all cases, but only when of the many senses some are true and others
are false. This manner of argument, however, does not belong
properly to dialectic; dialecticians should therefore by all means
beware of this kind of verbal discussion, unless any one is absolutely
unable to discuss the subject before him in any other way.
  The discovery of the differences of things helps us both in
reasonings about sameness and difference, and also in recognizing what
any particular thing is. That it helps us in reasoning about
sameness and difference is clear: for when we have discovered a
difference of any kind whatever between the objects before us, we
shall already have shown that they are not the same: while it helps us
in recognizing what a thing is, because we usually distinguish the
expression that is proper to the essence of each particular thing by
means of the differentiae that are proper to it.
  The examination of likeness is useful with a view both to
inductive arguments and to hypothetical reasonings, and also with a
view to the rendering of definitions. It is useful for inductive
arguments, because it is by means of an induction of individuals in
cases that are alike that we claim to bring the universal in evidence:
for it is not easy to do this if we do not know the points of
likeness. It is useful for hypothetical reasonings because it is a
general opinion that among similars what is true of one is true also
of the rest. If, then, with regard to any of them we are well supplied
with matter for a discussion, we shall secure a preliminary
admission that however it is in these cases, so it is also in the case
before us: then when we have shown the former we shall have shown,
on the strength of the hypothesis, the matter before us as well: for
we have first made the hypothesis that however it is in these cases,
so it is also in the case before us, and have then proved the point as
regards these cases. It is useful for the rendering of definitions
because, if we are able to see in one glance what is the same in
each individual case of it, we shall be at no loss into what genus
we ought to put the object before us when we define it: for of the
common predicates that which is most definitely in the category of
essence is likely to be the genus. Likewise, also, in the case of
objects widely divergent, the examination of likeness is useful for
purposes of definition, e.g. the sameness of a calm at sea, and
windlessness in the air (each being a form of rest), and of a point on
a line and the unit in number-each being a starting point. If, then,
we render as the genus what is common to all the cases, we shall get
the credit of defining not inappropriately. Definition-mongers too
nearly always render them in this way: they declare the unit to be the
startingpoint of number, and the point the startingpoint of a line. It
is clear, then, that they place them in that which is common to both
as their genus.
  The means, then, whereby reasonings are effected, are these: the
commonplace rules, for the observance of which the aforesaid means are
useful, are as follows.

                              Book II
                                 1

  Of problems some are universal, others particular. Universal
problems are such as 'Every pleasure is good' and 'No pleasure is
good'; particular problems are such as 'Some pleasure is good' and
'Some pleasure is not good'. The methods of establishing and
overthrowing a view universally are common to both kinds of
problems; for when we have shown that a predicate belongs in every
case, we shall also have shown that it belongs in some cases.
Likewise, also, if we show that it does not belong in any case, we
shall also have shown that it does not belong in every case. First,
then, we must speak of the methods of overthrowing a view universally,
because such are common to both universal and particular problems, and
because people more usually introduce theses asserting a predicate
than denying it, while those who argue with them overthrow it. The
conversion of an appropriate name which is drawn from the element
'accident' is an extremely precarious thing; for in the case of
accidents and in no other it is possible for something to be true
conditionally and not universally. Names drawn from the elements
'definition' and 'property' and 'genus' are bound to be convertible;
e.g. if 'to be an animal that walks on two feet is an attribute of S',
then it will be true by conversion to say that 'S is an animal that
walks on two feet'. Likewise, also, if drawn from the genus; for if
'to be an animal is an attribute of S', then 'S is an animal'. The
same is true also in the case of a property; for if 'to be capable
of learning grammar is an attribute of S', then 'S will be capable
of learning grammar'. For none of these attributes can possibly belong
or not belong in part; they must either belong or not belong
absolutely. In the case of accidents, on the other hand, there is
nothing to prevent an attribute (e.g. whiteness or justice)
belonging in part, so that it is not enough to show that whiteness
or justice is an attribute of a man in order to show that he is
white or just; for it is open to dispute it and say that he is white
or just in part only. Conversion, then, is not a necessary process
in the case of accidents.
  We must also define the errors that occur in problems. They are of
two kinds, caused either by false statement or by transgression of the
established diction. For those who make false statements, and say that
an attribute belongs to thing which does not belong to it, commit
error; and those who call objects by the names of other objects
(e.g. calling a planetree a 'man') transgress the established
terminology.

                                 2

  Now one commonplace rule is to look and see if a man has ascribed as
an accident what belongs in some other way. This mistake is most
commonly made in regard to the genera of things, e.g. if one were to
say that white happens (accidit) to be a colour-for being a colour
does not happen by accident to white, but colour is its genus. The
assertor may of course define it so in so many words, saying (e.g.)
that 'Justice happens (accidit) to be a virtue'; but often even
without such definition it is obvious that he has rendered the genus
as an accident; e.g. suppose that one were to say that whiteness is
coloured or that walking is in motion. For a predicate drawn from
the genus is never ascribed to the species in an inflected form, but
always the genera are predicated of their species literally; for the
species take on both the name and the definition of their genera. A
man therefore who says that white is 'coloured' has not rendered
'coloured' as its genus, seeing that he has used an inflected form,
nor yet as its property or as its definition: for the definition and
property of a thing belong to it and to nothing else, whereas many
things besides white are coloured, e.g. a log, a stone, a man, and a
horse. Clearly then he renders it as an accident.
  Another rule is to examine all cases where a predicate has been
either asserted or denied universally to belong to something. Look
at them species by species, and not in their infinite multitude: for
then the inquiry will proceed more directly and in fewer steps. You
should look and begin with the most primary groups, and then proceed
in order down to those that are not further divisible: e.g. if a man
has said that the knowledge of opposites is the same, you should
look and see whether it be so of relative opposites and of
contraries and of terms signifying the privation or presence of
certain states, and of contradictory terms. Then, if no clear result
be reached so far in these cases, you should again divide these
until you come to those that are not further divisible, and see (e.g.)
whether it be so of just deeds and unjust, or of the double and the
half, or of blindness and sight, or of being and not-being: for if
in any case it be shown that the knowledge of them is not the same
we shall have demolished the problem. Likewise, also, if the predicate
belongs in no case. This rule is convertible for both destructive
and constructive purposes: for if, when we have suggested a
division, the predicate appears to hold in all or in a large number of
cases, we may then claim that the other should actually assert it
universally, or else bring a negative instance to show in what case it
is not so: for if he does neither of these things, a refusal to assert
it will make him look absurd.
  Another rule is to make definitions both of an accident and of its
subject, either of both separately or else of one of them, and then
look and see if anything untrue has been assumed as true in the
definitions. Thus (e.g.) to see if it is possible to wrong a god,
ask what is 'to wrong'? For if it be 'to injure deliberately', clearly
it is not possible for a god to be wronged: for it is impossible
that God should be injured. Again, to see if the good man is
jealous, ask who is the 'jealous' man and what is 'jealousy'. For if
'jealousy' is pain at the apparent success of some well-behaved
person, clearly the good man is not jealous: for then he would be bad.
Again, to see if the indignant man is jealous, ask who each of them
is: for then it will be obvious whether the statement is true or
false; e.g. if he is 'jealous' who grieves at the successes of the
good, and he is 'indignant' who grieves at the successes of the
evil, then clearly the indignant man would not be jealous. A man
should substitute definitions also for the terms contained in his
definitions, and not stop until he comes to a familiar term: for often
if the definition be rendered whole, the point at issue is not cleared
up, whereas if for one of the terms used in the definition a
definition be stated, it becomes obvious.
  Moreover, a man should make the problem into a proposition for
himself, and then bring a negative instance against it: for the
negative instance will be a ground of attack upon the assertion.
This rule is very nearly the same as the rule to look into cases where
a predicate has been attributed or denied universally: but it
differs in the turn of the argument.
  Moreover, you should define what kind of things should be called
as most men call them, and what should not. For this is useful both
for establishing and for overthrowing a view: e.g. you should say that
we ought to use our terms to mean the same things as most people
mean by them, but when we ask what kind of things are or are not of
such and such a kind, we should not here go with the multitude: e.g.
it is right to call 'healthy' whatever tends to produce health, as
do most men: but in saying whether the object before us tends to
produce health or not, we should adopt the language no longer of the
multitude but of the doctor.

                                 3

  Moreover, if a term be used in several senses, and it has been
laid down that it is or that it is not an attribute of S, you should
show your case of one of its several senses, if you cannot show it
of both. This rule is to be observed in cases where the difference
of meaning is undetected; for supposing this to be obvious, then the
other man will object that the point which he himself questioned has
not been discussed, but only the other point. This commonplace rule is
convertible for purposes both of establishing and of overthrowing a
view. For if we want to establish a statement, we shall show that in
one sense the attribute belongs, if we cannot show it of both
senses: whereas if we are overthrowing a statement, we shall show that
in one sense the attribute does not belong, if we cannot show it of
both senses. Of course, in overthrowing a statement there is no need
to start the discussion by securing any admission, either when the
statement asserts or when it denies the attribute universally: for
if we show that in any case whatever the attribute does not belong, we
shall have demolished the universal assertion of it, and likewise also
if we show that it belongs in a single case, we shall demolish the
universal denial of it. Whereas in establishing a statement we ought
to secure a preliminary admission that if it belongs in any case
whatever, it belongs universally, supposing this claim to be a
plausible one. For it is not enough to discuss a single instance in
order to show that an attribute belongs universally; e.g. to argue
that if the soul of man be immortal, then every soul is immortal, so
that a previous admission must be secured that if any soul whatever be
immortal, then every soul is immortal. This is not to be done in every
case, but only whenever we are not easily able to quote any single
argument applying to all cases in common, as (e.g.) the geometrician
can argue that the triangle has its angles equal to two right angles.
  If, again, the variety of meanings of a term be obvious, distinguish
how many meanings it has before proceeding either to demolish or to
establish it: e.g. supposing 'the right' to mean 'the expedient' or
'the honourable', you should try either to establish or to demolish
both descriptions of the subject in question; e.g. by showing that
it is honourable and expedient, or that it is neither honourable nor
expedient. Supposing, however, that it is impossible to show both, you
should show the one, adding an indication that it is true in the one
sense and not in the other. The same rule applies also when the number
of senses into which it is divided is more than two.
  Again, consider those expressions whose meanings are many, but
differ not by way of ambiguity of a term, but in some other way:
e.g. 'The science of many things is one': here 'many things' may
mean the end and the means to that end, as (e.g.) medicine is the
science both of producing health and of dieting; or they may be both
of them ends, as the science of contraries is said to be the same (for
of contraries the one is no more an end than the other); or again they
may be an essential and an accidental attribute, as (e.g.) the
essential fact that the triangle has its angles equal to two right
angles, and the accidental fact that the equilateral figure has them
so: for it is because of the accident of the equilateral triangle
happening to be a triangle that we know that it has its angles equal
to two right angles. If, then, it is not possible in any sense of
the term that the science of many things should be the same, it
clearly is altogether impossible that it should be so; or, if it is
possible in some sense, then clearly it is possible. Distinguish as
many meanings as are required: e.g. if we want to establish a view, we
should bring forward all such meanings as admit that view and should
divide them only into those meanings which also are required for the
establishment of our case: whereas if we want to overthrow a view,
we should bring forward all that do not admit that view, and leave the
rest aside. We must deal also in these cases as well with any
uncertainty about the number of meanings involved. Further, that one
thing is, or is not, 'of' another should be established by means of
the same commonplace rules; e.g. that a particular science is of a
particular thing, treated either as an end or as a means to its end,
or as accidentally connected with it; or again that it is not 'of'
it in any of the aforesaid ways. The same rule holds true also of
desire and all other terms that have more than one object. For the
'desire of X' may mean the desire of it as an end (e.g. the desire
of health) or as a means to an end (e.g. the desire of being
doctored), or as a thing desired accidentally, as, in the case of
wine, the sweet-toothed person desires it not because it is wine but
because it is sweet. For essentially he desires the sweet, and only
accidentally the wine: for if it be dry, he no longer desires it.
His desire for it is therefore accidental. This rule is useful in
dealing with relative terms: for cases of this kind are generally
cases of relative terms.

                                 4

  Moreover, it is well to alter a term into one more familiar, e.g. to
substitute 'clear' for 'exact' in describing a conception, and
'being fussy' for 'being busy': for when the expression is made more
familiar, the thesis becomes easier to attack. This commonplace rule
also is available for both purposes alike, both for establishing and
for overthrowing a view.
  In order to show that contrary attributes belong to the same
thing, look at its genus; e.g. if we want to show that rightness and
wrongness are possible in regard to perception, and to perceive is
to judge, while it is possible to judge rightly or wrongly, then in
regard to perception as well rightness and wrongness must be possible.
In the present instance the proof proceeds from the genus and
relates to the species: for 'to judge' is the genus of 'to -perceive';
for the man who perceives judges in a certain way. But per contra it
may proceed from the species to the genus: for all the attributes that
belong to the species belong to the genus as well; e.g. if there is
a bad and a good knowledge there is also a bad and a good disposition:
for 'disposition' is the genus of knowledge. Now the former
commonplace argument is fallacious for purposes of establishing a
view, while the second is true. For there is no necessity that all the
attributes that belong to the genus should belong also to the species;
for 'animal' is flying and quadruped, but not so 'man'. All the
attributes, on the other hand, that belong to the species must of
necessity belong also to the genus; for if 'man' is good, then
animal also is good. On the other hand, for purposes of overthrowing a
view, the former argument is true while the latter is fallacious;
for all the attributes which do not belong to the genus do not
belong to the species either; whereas all those that are wanting to
the species are not of necessity wanting to the genus.
  Since those things of which the genus is predicated must also of
necessity have one of its species predicated of them, and since
those things that are possessed of the genus in question, or are
described by terms derived from that genus, must also of necessity
be possessed of one of its species or be described by terms derived
from one of its species (e.g. if to anything the term 'scientific
knowledge' be applied, then also there will be applied to it the
term 'grammatical' or 'musical' knowledge, or knowledge of one of
the other sciences; and if any one possesses scientific knowledge or
is described by a term derived from 'science', then he will also
possess grammatical or musical knowledge or knowledge of one of the
other sciences, or will be described by a term derived from one of
them, e.g. as a 'grammarian' or a 'musician')-therefore if any
expression be asserted that is in any way derived from the genus (e.g.
that the soul is in motion), look and see whether it be possible for
the soul to be moved with any of the species of motion; whether (e.g.)
it can grow or be destroyed or come to be, and so forth with all the
other species of motion. For if it be not moved in any of these
ways, clearly it does not move at all. This commonplace rule is common
for both purposes, both for overthrowing and for establishing a
view: for if the soul moves with one of the species of motion, clearly
it does move; while if it does not move with any of the species of
motion, clearly it does not move.
  If you are not well equipped with an argument against the assertion,
look among the definitions, real or apparent, of the thing before you,
and if one is not enough, draw upon several. For it will be easier
to attack people when committed to a definition: for an attack is
always more easily made on definitions.
  Moreover, look and see in regard to the thing in question, what it
is whose reality conditions the reality of the thing in question, or
what it is whose reality necessarily follows if the thing in
question be real: if you wish to establish a view inquire what there
is on whose reality the reality of the thing in question will follow
(for if the former be shown to be real, then the thing in question
will also have been shown to be real); while if you want to
overthrow a view, ask what it is that is real if the thing in question
be real, for if we show that what follows from the thing in question
is unreal, we shall have demolished the thing in question.
  Moreover, look at the time involved, to see if there be any
discrepancy anywhere: e.g. suppose a man to have stated that what is
being nourished of necessity grows: for animals are always of
necessity being nourished, but they do not always grow. Likewise,
also, if he has said that knowing is remembering: for the one is
concerned with past time, whereas the other has to do also with the
present and the future. For we are said to know things present and
future (e.g. that there will be an eclipse), whereas it is
impossible to remember anything save what is in the past.

                                 5

  Moreover, there is the sophistic turn of argument, whereby we draw
our opponent into the kind of statement against which we shall be well
supplied with lines of argument. This process is sometimes a real
necessity, sometimes an apparent necessity, sometimes neither an
apparent nor a real necessity. It is really necessary whenever the
answerer has denied any view that would be useful in attacking the
thesis, and the questioner thereupon addresses his arguments to the
support of this view, and when moreover the view in question happens
to be one of a kind on which he has a good stock of lines of argument.
Likewise, also, it is really necessary whenever he (the questioner)
first, by an induction made by means of the view laid down, arrives at
a certain statement and then tries to demolish that statement: for
when once this has been demolished, the view originally laid down is
demolished as well. It is an apparent necessity, when the point to
which the discussion comes to be directed appears to be useful, and
relevant to the thesis, without being really so; whether it be that
the man who is standing up to the argument has refused to concede
something, or whether he (the questioner) has first reached it by a
plausible induction based upon the thesis and then tries to demolish
it. The remaining case is when the point to which the discussion comes
to be directed is neither really nor apparently necessary, and it is
the answerer's luck to be confuted on a mere side issue You should
beware of the last of the aforesaid methods; for it appears to be
wholly disconnected from, and foreign to, the art of dialectic. For
this reason, moreover, the answerer should not lose his temper, but
assent to those statements that are of no use in attacking the thesis,
adding an indication whenever he assents although he does not agree
with the view. For, as a rule, it increases the confusion of
questioners if, after all propositions of this kind have been
granted them, they can then draw no conclusion.
  Moreover, any one who has made any statement whatever has in a
certain sense made several statements, inasmuch as each statement
has a number of necessary consequences: e.g. the man who said 'X is
a man' has also said that it is an animal and that it is animate and a
biped and capable of acquiring reason and knowledge, so that by the
demolition of any single one of these consequences, of whatever
kind, the original statement is demolished as well. But you should
beware here too of making a change to a more difficult subject: for
sometimes the consequence, and sometimes the original thesis, is the
easier to demolish.

                                 6

  In regard to subjects which must have one and one only of two
predicates, as (e.g.) a man must have either a disease or health,
supposing we are well supplied as regards the one for arguing its
presence or absence, we shall be well equipped as regards the
remaining one as well. This rule is convertible for both purposes: for
when we have shown that the one attribute belongs, we shall have shown
that the remaining one does not belong; while if we show that the
one does not belong, we shall have shown that the remaining one does
belong. Clearly then the rule is useful for both purposes.
  Moreover, you may devise a line of attack by reinterpreting a term
in its literal meaning, with the implication that it is most fitting
so to take it rather than in its established meaning: e.g. the
expression 'strong at heart' will suggest not the courageous man,
according to the use now established, but the man the state of whose
heart is strong; just as also the expression 'of a good hope' may be
taken to mean the man who hopes for good things. Likewise also
'well-starred' may be taken to mean the man whose star is good, as
Xenocrates says 'well-starred is he who has a noble soul'.' For a
man's star is his soul.
  Some things occur of necessity, others usually, others however it
may chance; if therefore a necessary event has been asserted to
occur usually, or if a usual event (or, failing such an event
itself, its contrary) has been stated to occur of necessity, it always
gives an opportunity for attack. For if a necessary event has been
asserted to occur usually, clearly the speaker has denied an attribute
to be universal which is universal, and so has made a mistake: and
so he has if he has declared the usual attribute to be necessary:
for then he declares it to belong universally when it does not so
belong. Likewise also if he has declared the contrary of what is usual
to be necessary. For the contrary of a usual attribute is always a
comparatively rare attribute: e.g. if men are usually bad, they are
comparatively seldom good, so that his mistake is even worse if he has
declared them to be good of necessity. The same is true also if he has
declared a mere matter of chance to happen of necessity or usually;
for a chance event happens neither of necessity nor usually. If the
thing happens usually, then even supposing his statement does not
distinguish whether he meant that it happens usually or that it
happens necessarily, it is open to you to discuss it on the assumption
that he meant that it happens necessarily: e.g. if he has stated
without any distinction that disinherited persons are bad, you may
assume in discussing it that he means that they are so necessarily.
  Moreover, look and see also if he has stated a thing to be an
accident of itself, taking it to be a different thing because it has a
different name, as Prodicus used to divide pleasures into joy and
delight and good cheer: for all these are names of the same thing,
to wit, Pleasure. If then any one says that joyfulness is an
accidental attribute of cheerfulness, he would be declaring it to be
an accidental attribute of itself.

                                 7

  Inasmuch as contraries can be conjoined with each other in six ways,
and four of these conjunctions constitute a contrariety, we must grasp
the subject of contraries, in order that it may help us both in
demolishing and in establishing a view. Well then, that the modes of
conjunction are six is clear: for either (1) each of the contrary
verbs will be conjoined to each of the contrary objects; and this
gives two modes: e.g. to do good to friends and to do evil to enemies,
or per contra to do evil to friends and to do good to enemies. Or else
(2) both verbs may be attached to one object; and this too gives two
modes, e.g. to do good to friends and to do evil to friends, or to
do good to enemies and to do evil to enemies. Or (3) a single verb may
be attached to both objects: and this also gives two modes; e.g. to do
good to friends and to do good to enemies, or to do evil to friends
and evil to enemies.
  The first two then of the aforesaid conjunctions do not constitute
any contrariety; for the doing of good to friends is not contrary to
the doing of evil to enemies: for both courses are desirable and
belong to the same disposition. Nor is the doing of evil to friends
contrary to the doing of good to enemies: for both of these are
objectionable and belong to the same disposition: and one
objectionable thing is not generally thought to be the contrary of
another, unless the one be an expression denoting an excess, and the
other an expression denoting a defect: for an excess is generally
thought to belong to the class of objectionable things, and likewise
also a defect. But the other four all constitute a contrariety. For to
do good to friends is contrary to the doing of evil to friends: for it
proceeds from the contrary disposition, and the one is desirable,
and the other objectionable. The case is the same also in regard to
the other conjunctions: for in each combination the one course is
desirable, and the other objectionable, and the one belongs to a
reasonable disposition and the other to a bad. Clearly, then, from
what has been said, the same course has more than one contrary. For
the doing of good to friends has as its contrary both the doing of
good to enemies and the doing of evil to friends. Likewise, if we
examine them in the same way, we shall find that the contraries of
each of the others also are two in number. Select therefore
whichever of the two contraries is useful in attacking the thesis.
  Moreover, if the accident of a thing have a contrary, see whether it
belongs to the subject to which the accident in question has been
declared to belong: for if the latter belongs the former could not
belong; for it is impossible that contrary predicates should belong at
the same time to the same thing.
  Or again, look and see if anything has been said about something, of
such a kind that if it be true, contrary predicates must necessarily
belong to the thing: e.g. if he has said that the 'Ideas' exist in us.
For then the result will be that they are both in motion and at
rest, and moreover that they are objects both of sensation and of
thought. For according to the views of those who posit the existence
of Ideas, those Ideas are at rest and are objects of thought; while if
they exist in us, it is impossible that they should be unmoved: for
when we move, it follows necessarily that all that is in us moves with
us as well. Clearly also they are objects of sensation, if they
exist in us: for it is through the sensation of sight that we
recognize the Form present in each individual.
  Again, if there be posited an accident which has a contrary, look
and see if that which admits of the accident will admit of its
contrary as well: for the same thing admits of contraries. Thus (e.g.)
if he has asserted that hatred follows anger, hatred would in that
case be in the 'spirited faculty': for that is where anger is. You
should therefore look and see if its contrary, to wit, friendship,
be also in the 'spirited faculty': for if not-if friendship is in
the faculty of desire-then hatred could not follow anger. Likewise
also if he has asserted that the faculty of desire is ignorant. For if
it were capable of ignorance, it would be capable of knowledge as
well: and this is not generally held-I mean that the faculty of desire
is capable of knowledge. For purposes, then, of overthrowing a view,
as has been said, this rule should be observed: but for purposes of
establishing one, though the rule will not help you to assert that the
accident actually belongs, it will help you to assert that it may
possibly belong. For having shown that the thing in question will
not admit of the contrary of the accident asserted, we shall have
shown that the accident neither belongs nor can possibly belong; while
on the other hand, if we show that the contrary belongs, or that the
thing is capable of the contrary, we shall not indeed as yet have
shown that the accident asserted does belong as well; our proof will
merely have gone to this point, that it is possible for it to belong.

                                 8

  Seeing that the modes of opposition are four in number, you should
look for arguments among the contradictories of your terms, converting
the order of their sequence, both when demolishing and when
establishing a view, and you should secure them by means of
induction-such arguments (e.g.) as that man be an animal, what is
not an animal is not a man': and likewise also in other instances of
contradictories. For in those cases the sequence is converse: for
'animal' follows upon 'man but 'not-animal' does not follow upon
'not-man', but conversely 'not-man' upon 'not-animal'. In all cases,
therefore, a postulate of this sort should be made, (e.g.) that 'If
the honourable is pleasant, what is not pleasant is not honourable,
while if the latter be untrue, so is the former'. Likewise, also,
'If what is not pleasant be not honourable, then what is honourable is
pleasant'. Clearly, then, the conversion of the sequence formed by
contradiction of the terms of the thesis is a method convertible for
both purposes.
  Then look also at the case of the contraries of S and P in the
thesis, and see if the contrary of the one follows upon the contrary
of the other, either directly or conversely, both when you are
demolishing and when you are establishing a view: secure arguments
of this kind as well by means of induction, so far as may be required.
Now the sequence is direct in a case such as that of courage and
cowardice: for upon the one of them virtue follows, and vice upon
the other; and upon the one it follows that it is desirable, while
upon the other it follows that it is objectionable. The sequence,
therefore, in the latter case also is direct; for the desirable is the
contrary of the objectionable. Likewise also in other cases. The
sequence is, on the other hand, converse in such a case as this:
Health follows upon vigour, but disease does not follow upon debility;
rather debility follows upon disease. In this case, then, clearly
the sequence is converse. Converse sequence is, however, rare in the
case of contraries; usually the sequence is direct. If, therefore, the
contrary of the one term does not follow upon the contrary of the
other either directly or conversely, clearly neither does the one term
follow upon the other in the statement made: whereas if the one
followed the other in the case of the contraries, it must of necessity
do so as well in the original statement.
  You should look also into cases of the privation or presence of a
state in like manner to the case of contraries. Only, in the case of
such privations the converse sequence does not occur: the sequence
is always bound to be direct: e.g. as sensation follows sight, while
absence of sensation follows blindness. For the opposition of
sensation to absence of sensation is an opposition of the presence
to the privation of a state: for the one of them is a state, and the
other the privation of it.
  The case of relative terms should also be studied in like manner
to that of a state and its privation: for the sequence of these as
well is direct; e.g. if 3/1 is a multiple, then 1/3 is a fraction: for
3/1 is relative to 1/3, and so is a multiple to a fraction. Again,
if knowledge be a conceiving, then also the object of knowledge is
an object of conception; and if sight be a sensation, then also the
object of sight is an object of sensation. An objection may be made
that there is no necessity for the sequence to take place, in the case
of relative terms, in the way described: for the object of sensation
is an object of knowledge, whereas sensation is not knowledge. The
objection is, however, not generally received as really true; for many
people deny that there is knowledge of objects of sensation. Moreover,
the principle stated is just as useful for the contrary purpose,
e.g. to show that the object of sensation is not an object of
knowledge, on the ground that neither is sensation knowledge.

                                 9

  Again look at the case of the co-ordinates and inflected forms of
the terms in the thesis, both in demolishing and in establishing it.
By co-ordinates' are meant terms such as the following: 'Just deeds'
and the 'just man' are coordinates of 'justice', and 'courageous
deeds' and the 'courageous man' are co-ordinates of courage.
Likewise also things that tend to produce and to preserve anything are
called co-ordinates of that which they tend to produce and to
preserve, as e.g. 'healthy habits' are co-ordinates of 'health' and
a 'vigorous constitutional' of a 'vigorous constitution' and so
forth also in other cases. 'Co-ordinate', then, usually describes
cases such as these, whereas 'inflected forms' are such as the
following: 'justly', 'courageously', 'healthily', and such as are
formed in this way. It is usually held that words when used in their
inflected forms as well are co-ordinates, as (e.g.) 'justly' in
relation to justice, and 'courageously' to courage; and then
'co-ordinate' describes all the members of the same kindred series,
e.g. 'justice', 'just', of a man or an act, 'justly'. Clearly, then,
when any one member, whatever its kind, of the same kindred series
is shown to be good or praiseworthy, then all the rest as well come to
be shown to be so: e.g. if 'justice' be something praiseworthy, then
so will 'just', of a man or thing, and 'justly' connote something
praiseworthy. Then 'justly' will be rendered also 'praiseworthily',
derived will by the same inflexion from 'the praiseworthy' whereby
'justly' is derived from 'justice'.
  Look not only in the case of the subject mentioned, but also in
the case of its contrary, for the contrary predicate: e.g. argue
that good is not necessarily pleasant; for neither is evil painful: or
that, if the latter be the case, so is the former. Also, if justice be
knowledge, then injustice is ignorance: and if 'justly' means
'knowingly' and 'skilfully', then 'unjustly' means 'ignorantly' and
'unskilfully': whereas if the latter be not true, neither is the
former, as in the instance given just now: for 'unjustly' is more
likely to seem equivalent to 'skilfully' than to 'unskilfully'. This
commonplace rule has been stated before in dealing with the sequence
of contraries; for all we are claiming now is that the contrary of P
shall follow the contrary of S.
  Moreover, look at the modes of generation and destruction of a
thing, and at the things which tend to produce or to destroy it,
both in demolishing and in establishing a view. For those things whose
modes of generation rank among good things, are themselves also
good; and if they themselves be good, so also are their modes of
generation. If, on the other hand, their modes of generation be
evil, then they themselves also are evil. In regard to modes of
destruction the converse is true: for if the modes of destruction rank
as good things, then they themselves rank as evil things; whereas if
the modes of destruction count as evil, they themselves count as good.
The same argument applies also to things tending to produce and
destroy: for things whose productive causes are good, themselves
also rank as good; whereas if causes destructive of them are good,
they themselves rank as evil.

                                10

  Again, look at things which are like the subject in question, and
see if they are in like case; e.g. if one branch of knowledge has more
than one object, so also will one opinion; and if to possess sight
be to see, then also to possess hearing will be to hear. Likewise also
in the case of other things, both those which are and those which
are generally held to be like. The rule in question is useful for both
purposes; for if it be as stated in the case of some one like thing,
it is so with the other like things as well, whereas if it be not so
in the case of some one of them, neither is it so in the case of the
others. Look and see also whether the cases are alike as regards a
single thing and a number of things: for sometimes there is a
discrepancy. Thus, if to 'know' a thing be to 'think of' it, then also
to 'know many things' is to 'be thinking of many things'; whereas this
is not true; for it is possible to know many things but not to be
thinking of them. If, then, the latter proposition be not true,
neither was the former that dealt with a single thing, viz. that to
'know' a thing is to 'think of' it.
  Moreover, argue from greater and less degrees. In regard to
greater degrees there are four commonplace rules. One is: See
whether a greater degree of the predicate follows a greater degree
of the subject: e.g. if pleasure be good, see whether also a greater
pleasure be a greater good: and if to do a wrong be evil, see
whether also to do a greater wrong is a greater evil. Now this rule is
of use for both purposes: for if an increase of the accident follows
an increase of the subject, as we have said, clearly the accident
belongs; while if it does not follow, the accident does not belong.
You should establish this by induction. Another rule is: If one
predicate be attributed to two subjects; then supposing it does not
belong to the subject to which it is the more likely to belong,
neither does it belong where it is less likely to belong; while if
it does belong where it is less likely to belong, then it belongs as
well where it is more likely. Again: If two predicates be attributed
to one subject, then if the one which is more generally thought to
belong does not belong, neither does the one that is less generally
thought to belong; or, if the one that is less generally thought to
belong does belong, so also does the other. Moreover: If two
predicates be attributed to two subjects, then if the one which is
more usually thought to belong to the one subject does not belong,
neither does the remaining predicate belong to the remaining
subject; or, if the one which is less usually thought to belong to the
one subject does belong, so too does the remaining predicate to the
remaining subject.
  Moreover, you can argue from the fact that an attribute belongs,
or is generally supposed to belong, in a like degree, in three ways,
viz. those described in the last three rules given in regard to a
greater degree.' For supposing that one predicate belongs, or is
supposed to belong, to two subjects in a like degree, then if it
does not belong to the one, neither does it belong to the other; while
if it belongs to the one, it belongs to the remaining one as well. Or,
supposing two predicates to belong in a like degree to the same
subject, then, if the one does not belong, neither does the
remaining one; while if the one does belong, the remaining one belongs
as well. The case is the same also if two predicates belong in a
like degree to two subjects; for if the one predicate does not
belong to the one subject, neither does the remaining predicate belong
to the remaining subject, while if the one predicate does belong to
the one subject, the remaining predicate belongs to the remaining
subject as well.

                                11

  You can argue, then, from greater or less or like degrees of truth
in the aforesaid number of ways. Moreover, you should argue from the
addition of one thing to another. If the addition of one thing to
another makes that other good or white, whereas formerly it was not
white or good, then the thing added will be white or good-it will
possess the character it imparts to the whole as well. Moreover, if an
addition of something to a given object intensifies the character
which it had as given, then the thing added will itself as well be
of that character. Likewise, also, in the case of other attributes.
The rule is not applicable in all cases, but only in those in which
the excess described as an 'increased intensity' is found to take
place. The above rule is, however, not convertible for overthrowing
a view. For if the thing added does not make the other good, it is not
thereby made clear whether in itself it may not be good: for the
addition of good to evil does not necessarily make the whole good, any
more than the addition of white to black makes the whole white.
  Again, any predicate of which we can speak of greater or less
degrees belongs also absolutely: for greater or less degrees of good
or of white will not be attributed to what is not good or white: for a
bad thing will never be said to have a greater or less degree of
goodness than another, but always of badness. This rule is not
convertible, either, for the purpose of overthrowing a predication:
for several predicates of which we cannot speak of a greater degree
belong absolutely: for the term 'man' is not attributed in greater and
less degrees, but a man is a man for all that.
  You should examine in the same way predicates attributed in a
given respect, and at a given time and place: for if the predicate
be possible in some respect, it is possible also absolutely. Likewise,
also, is what is predicated at a given time or place: for what is
absolutely impossible is not possible either in any respect or at
any place or time. An objection may be raised that in a given
respect people may be good by nature, e.g. they may be generous or
temperately inclined, while absolutely they are not good by nature,
because no one is prudent by nature. Likewise, also, it is possible
for a destructible thing to escape destruction at a given time,
whereas it is not possible for it to escape absolutely. In the same
way also it is a good thing at certain places to follow see and such a
diet, e.g. in infected areas, though it is not a good thing
absolutely. Moreover, in certain places it is possible to live
singly and alone, but absolutely it is not possible to exist singly
and alone. In the same way also it is in certain places honourable
to sacrifice one's father, e.g. among the Triballi, whereas,
absolutely, it is not honourable. Or possibly this may indicate a
relativity not to places but to persons: for it is all the same
wherever they may be: for everywhere it will be held honourable
among the Triballi themselves, just because they are Triballi.
Again, at certain times it is a good thing to take medicines, e.g.
when one is ill, but it is not so absolutely. Or possibly this again
may indicate a relativity not to a certain time, but to a certain
state of health: for it is all the same whenever it occurs, if only
one be in that state. A thing is 'absolutely' so which without any
addition you are prepared to say is honourable or the contrary. Thus
(e.g.) you will deny that to sacrifice one's father is honourable:
it is honourable only to certain persons: it is not therefore
honourable absolutely. On the other hand, to honour the gods you
will declare to be honourable without adding anything, because that is
honourable absolutely. So that whatever without any addition is
generally accounted to be honourable or dishonourable or anything else
of that kind, will be said to be so 'absolutely'.

                              Book III
                                 1

  THE question which is the more desirable, or the better, of two or
more things, should be examined upon the following lines: only first
of all it must be clearly laid down that the inquiry we are making
concerns not things that are widely divergent and that exhibit great
differences from one another (for nobody raises any doubt whether
happiness or wealth is more desirable), but things that are nearly
related and about which we commonly discuss for which of the two we
ought rather to vote, because we do not see any advantage on either
side as compared with the other. Clearly, in such cases if we can show
a single advantage, or more than one, our judgement will record our
assent that whichever side happens to have the advantage is the more
desirable.
  First, then, that which is more lasting or secure is more
desirable than that which is less so: and so is that which is more
likely to be chosen by the prudent or by the good man or by the
right law, or by men who are good in any particular line, when they
make their choice as such, or by the experts in regard to any
particular class of things; i.e. either whatever most of them or
what all of them would choose; e.g. in medicine or in carpentry
those things are more desirable which most, or all, doctors would
choose; or, in general, whatever most men or all men or all things
would choose, e.g. the good: for everything aims at the good. You
should direct the argument you intend to employ to whatever purpose
you require. Of what is 'better' or 'more desirable' the absolute
standard is the verdict of the better science, though relatively to
a given individual the standard may be his own particular science.
  In the second place, that which is known as 'an x' is more desirable
than that which does not come within the genus 'x'-e.g. justice than a
just man; for the former falls within the genus 'good', whereas the
other does not, and the former is called 'a good', whereas the
latter is not: for nothing which does not happen to belong to the
genus in question is called by the generic name; e.g. a 'white man' is
not 'a colour'. Likewise also in other cases.
  Also, that which is desired for itself is more desirable than that
which is desired for something else; e.g. health is more desirable
than gymnastics: for the former is desired for itself, the latter
for something else. Also, that which is desirable in itself is more
desirable than what is desirable per accidens; e.g. justice in our
friends than justice in our enemies: for the former is desirable in
itself, the latter per accidens: for we desire that our enemies should
be just per accidens, in order that they may do us no harm. This
last principle is the same as the one that precedes it, with, however,
a different turn of expression. For we desire justice in our friends
for itself, even though it will make no difference to us, and even
though they be in India; whereas in our enemies we desire it for
something else, in order that they may do us no harm.
  Also, that which is in itself the cause of good is more desirable
than what is so per accidens, e.g. virtue than luck (for the former in
itself, and the latter per accidens, the cause of good things), and so
in other cases of the same kind. Likewise also in the case of the
contrary; for what is in itself the cause of evil is more
objectionable than what is so per accidens, e.g. vice and chance:
for the one is bad in itself, whereas chance is so per accidens.
  Also, what is good absolutely is more desirable than what is good
for a particular person, e.g. recovery of health than a surgical
operation; for the former is good absolutely, the latter only for a
particular person, viz. the man who needs an operation. So too what is
good by nature is more desirable than the good that is not so by
nature, e.g. justice than the just man; for the one is good by nature,
whereas in the other case the goodness is acquired. Also the attribute
is more desirable which belongs to the better and more honourable
subject, e.g. to a god rather than to a man, and to the soul rather
than to the body. So too the property of the better thing is better
than the property of the worse; e.g. the property of God than the
property of man: for whereas in respect of what is common in both of
them they do not differ at all from each other, in respect of their
properties the one surpasses the other. Also that is better which is
inherent in things better or prior or more honourable: thus (e.g.)
health is better than strength and beauty: for the former is
inherent in the moist and the dry, and the hot and the cold, in fact
in all the primary constituents of an animal, whereas the others are
inherent in what is secondary, strength being a feature of the
sinews and bones, while beauty is generally supposed to consist in a
certain symmetry of the limbs. Also the end is generally supposed to
be more desirable than the means, and of two means, that which lies
nearer the end. In general, too, a means directed towards the end of
life is more desirable than a means to anything else, e.g. that
which contributes to happiness than that which contributes to
prudence. Also the competent is more desirable than the incompetent.
Moreover, of two productive agents that one is more desirable whose
end is better; while between a productive agent and an end we can
decide by a proportional sum whenever the excess of the one end over
the other is greater than that of the latter over its own productive
means: e.g. supposing the excess of happiness over health to be
greater than that of health over what produces health, then what
produces happiness is better than health. For what produces
happiness exceeds what produces health just as much as happiness
exceeds health. But health exceeds what produces health by a smaller
amount; ergo, the excess of what produces happiness over what produces
health is greater than that of health over what produces health.
Clearly, therefore, what produces happiness is more desirable than
health: for it exceeds the same standard by a greater amount.
Moreover, what is in itself nobler and more precious and
praiseworthy is more desirable than what is less so, e.g. friendship
than wealth, and justice than strength. For the former belong in
themselves to the class of things precious and praiseworthy, while the
latter do so not in themselves but for something else: for no one
prizes wealth for itself but always for something else, whereas we
prize friendship for itself, even though nothing else is likely to
come to us from it.

                                 2

  Moreover, whenever two things are very much like one another, and we
cannot see any superiority in the one over the other of them, we
should look at them from the standpoint of their consequences. For the
one which is followed by the greater good is the more desirable: or,
if the consequences be evil, that is more desirable which is
followed by the less evil. For though both may be desirable, yet there
may possibly be some unpleasant consequence involved to turn the
scale. Our survey from the point of view of consequences lies in two
directions, for there are prior consequences and later consequences:
e.g. if a man learns, it follows that he was ignorant before and knows
afterwards. As a rule, the later consequence is the better to
consider. You should take, therefore, whichever of the consequences
suits your purpose.
  Moreover, a greater number of good things is more desirable than a
smaller, either absolutely or when the one is included in the other,
viz. the smaller number in the greater. An objection may be raised
suppose in some particular case the one is valued for the sake of
the other; for then the two together are not more desirable than the
one; e.g. recovery of health and health, than health alone, inasmuch
as we desire recovery of health for the sake of health. Also it is
quite possible for what is not good, together with what is, to be more
desirable than a greater number of good things, e.g. the combination
of happiness and something else which is not good may be more
desirable than the combination of justice and courage. Also, the
same things are more valuable if accompanied than if unaccompanied
by pleasure, and likewise when free from pain than when attended
with pain.
  Also, everything is more desirable at the season when it is of
greater consequence; e.g. freedom from pain in old age more than in
youth: for it is of greater consequence in old age. On the same
principle also, prudence is more desirable in old age; for no man
chooses the young to guide him, because he does not expect them to
be prudent. With courage, the converse is the case, for it is in youth
that the active exercise of courage is more imperatively required.
Likewise also with temperance; for the young are more troubled by
their passions than are their elders.
  Also, that is more desirable which is more useful at every season or
at most seasons, e.g. justice and temperance rather than courage:
for they are always useful, while courage is only useful at times.
Also, that one of two things which if all possess, we do not need
the other thing, is more desirable than that which all may possess and
still we want the other one as well. Take the case of justice and
courage; if everybody were just, there would be no use for courage,
whereas all might be courageous, and still justice would be of use.
  Moreover, judge by the destructions and losses and generations and
acquisitions and contraries of things: for things whose destruction is
more objectionable are themselves more desirable. Likewise also with
the losses and contraries of things; for a thing whose loss or whose
contrary is more objectionable is itself more desirable. With the
generations or acquisitions of things the opposite is the case: for
things whose acquisition or generation is more desirable are
themselves also desirable. Another commonplace rule is that what is
nearer to the good is better and more desirable, i.e. what more nearly
resembles the good: thus justice is better than a just man. Also, that
which is more like than another thing to something better than itself,
as e.g. some say that Ajax was a better man than Odysseus because he
was more like Achilles. An objection may be raised to this that it
is not true: for it is quite possible that Ajax did not resemble
Achilles more nearly than Odysseus in the points which made Achilles
the best of them, and that Odysseus was a good man, though unlike
Achilles. Look also to see whether the resemblance be that of a
caricature, like the resemblance of a monkey to a man, whereas a horse
bears none: for the monkey is not the more handsome creature,
despite its nearer resemblance to a man. Again, in the case of two
things, if one is more like the better thing while another is more
like the worse, then that is likely to be better which is more like
the better. This too, however, admits of an objection: for quite
possibly the one only slightly resembles the better, while the other
strongly resembles the worse, e.g. supposing the resemblance of Ajax
to Achilles to be slight, while that of Odysseus to Nestor is
strong. Also it may be that the one which is like the better type
shows a degrading likeness, whereas the one which is like the worse
type improves upon it: witness the likeness of a horse to a donkey,
and that of a monkey to a man.
  Another rule is that the more conspicuous good is more desirable
than the less conspicuous, and the more difficult than the easier: for
we appreciate better the possession of things that cannot be easily
acquired. Also the more personal possession is more desirable than the
more widely shared. Also, that which is more free from connexion
with evil: for what is not attended by any unpleasantness is more
desirable than what is so attended.
  Moreover, if A be without qualification better than B, then also the
best of the members of A is better than the best of the members of
B; e.g. if Man be better than Horse, then also the best man is
better than the best horse. Also, if the best in A be better than
the best in B, then also A is better than B without qualification;
e.g. if the best man be better than the best horse, then also Man is
better than Horse without qualification.
  Moreover, things which our friends can share are more desirable than
those they cannot. Also, things which we like rather to do to our
friend are more desirable than those we like to do to the man in the
street, e.g. just dealing and the doing of good rather than the
semblance of them: for we would rather really do good to our friends
than seem to do so, whereas towards the man in the street the converse
is the case.
  Also, superfluities are better than necessities, and are sometimes
more desirable as well: for the good life is better than mere life,
and good life is a superfluity, whereas mere life itself is a
necessity. Sometimes, though, what is better is not also more
desirable: for there is no necessity that because it is better it
should also be more desirable: at least to be a philosopher is
better than to make money, but it is not more desirable for a man
who lacks the necessities of life. The expression 'superfluity'
applies whenever a man possesses the necessities of life and sets to
work to secure as well other noble acquisitions. Roughly speaking,
perhaps, necessities are more desirable, while superfluities are
better.
  Also, what cannot be got from another is more desirable than what
can be got from another as well, as (e.g.) is the case of justice
compared with courage. Also, A is more desirable if A is desirable
without B, but not B without A: power (e.g.) is not desirable
without prudence, but prudence is desirable without power. Also, if of
two things we repudiate the one in order to be thought to possess
the other, then that one is more desirable which we wish to be thought
to possess; thus (e.g.) we repudiate the love of hard work in order
that people may think us geniuses.
  Moreover, that is more desirable in whose absence it is less
blameworthy for people to be vexed; and that is more desirable in
whose absence it is more blameworthy for a man not to be vexed.

                                 3

  Moreover, of things that belong to the same species one which
possesses the peculiar virtue of the species is more desirable than
one which does not. If both possess it, then the one which possesses
it in a greater degree is more desirable.
  Moreover, if one thing makes good whatever it touches, while another
does not, the former is more desirable, just as also what makes things
warm is warmer than what does not. If both do so, then that one is
more desirable which does so in a greater degree, or if it render good
the better and more important object-if (e.g.), the one makes good the
soul, and the other the body.
  Moreover, judge things by their inflexions and uses and actions
and works, and judge these by them: for they go with each other:
e.g. if 'justly' means something more desirable than 'courageously',
then also justice means something more desirable than courage; and
if justice be more desirable than courage, then also 'justly' means
something more desirable than 'courageously'. Similarly also in the
other cases.
  Moreover, if one thing exceeds while the other falls short of the
same standard of good, the one which exceeds is the more desirable; or
if the one exceeds an even higher standard. Nay more, if there be
two things both preferable to something, the one which is more
highly preferable to it is more desirable than the less highly
preferable. Moreover, when the excess of a thing is more desirable
than the excess of something else, that thing is itself also more
desirable than the other, as (e.g.) friendship than money: for an
excess of friendship is more desirable than an excess of money. So
also that of which a man would rather that it were his by his own
doing is more desirable than what he would rather get by another's
doing, e.g. friends than money. Moreover, judge by means of an
addition, and see if the addition of A to the same thing as B makes
the whole more desirable than does the addition of B. You must,
however, beware of adducing a case in which the common term uses, or
in some other way helps the case of, one of the things added to it,
but not the other, as (e.g.) if you took a saw and a sickle in
combination with the art of carpentry: for in the combination the
saw is a more desirable thing, but it is not a more desirable thing
without qualification. Again, a thing is more desirable if, when added
to a lesser good, it makes the whole greater good. Likewise, also, you
should judge by means of subtraction: for the thing upon whose
subtraction the remainder is a lesser good may be taken to be a
greater good, whichever it be whose subtraction makes the remainder
a lesser good.
  Also, if one thing be desirable for itself, and the other for the
look of it, the former is more desirable, as (e.g.) health than
beauty. A thing is defined as being desired for the look of it if,
supposing no one knew of it, you would not care to have it. Also, it
is more desirable both for itself and for the look of it, while the
other thing is desirable on the one ground alone. Also, whichever is
the more precious for itself, is also better and more desirable. A
thing may be taken to be more precious in itself which we choose
rather for itself, without anything else being likely to come of it.
  Moreover, you should distinguish in how many senses 'desirable' is
used, and with a view to what ends, e.g. expediency or honour or
pleasure. For what is useful for all or most of them may be taken to
be more desirable than what is not useful in like manner. If the
same characters belong to both things you should look and see which
possesses them more markedly, i.e. which of the two is the more
pleasant or more honourable or more expedient. Again, that is more
desirable which serves the better purpose, e.g. that which serves to
promote virtue more than that which serves to promote pleasure.
Likewise also in the case of objectionable things; for that is more
objectionable which stands more in the way of what is desirable,
e.g. disease more than ugliness: for disease is a greater hindrance
both to pleasure and to being good.
  Moreover, argue by showing that the thing in question is in like
measure objectionable and desirable: for a thing of such a character
that a man might well desire and object to it alike is less
desirable than the other which is desirable only.

                                 4

  Comparisons of things together should therefore be conducted in
the manner prescribed. The same commonplace rules are useful also
for showing that anything is simply desirable or objectionable: for we
have only to subtract the excess of one thing over another. For if
what is more precious be more desirable, then also what is precious is
desirable; and if what is more useful be more desirable, then also
what is useful is desirable. Likewise, also, in the case of other
things which admit of comparisons of that kind. For in some cases in
the very course of comparing the things together we at once assert
also that each of them, or the one of them, is desirable, e.g.
whenever we call the one good 'by nature' and the other 'not by
nature': for dearly what is good by nature is desirable.

                                 5

  The commonplace rules relating to comparative degrees and amounts
ought to be taken in the most general possible form: for when so taken
they are likely to be useful in a larger number of instances. It is
possible to render some of the actual rules given above more universal
by a slight alteration of the expression, e.g. that what by nature
exhibits such and such a quality exhibits that quality in a greater
degree than what exhibits it not by nature. Also, if one thing does,
and another does not, impart such and such a quality to that which
possesses it, or to which it belongs, then whichever does impart it is
of that quality in greater degree than the one which does not impart
it; and if both impart it, then that one exhibits it in a greater
degree which imparts it in a greater degree.
  Moreover, if in any character one thing exceeds and another falls
short of the same standard; also, if the one exceeds something which
exceeds a given standard, while the other does not reach that
standard, then clearly the first-named thing exhibits that character
in a greater degree. Moreover, you should judge by means of
addition, and see if A when added to the same thing as B imparts to
the whole such and such a character in a more marked degree than B, or
if, when added to a thing which exhibits that character in a less
degree, it imparts that character to the whole in a greater degree.
Likewise, also, you may judge by means of subtraction: for a thing
upon whose subtraction the remainder exhibits such and such a
character in a less degree, itself exhibits that character in a
greater degree. Also, things exhibit such and such a character in a
greater degree if more free from admixture with their contraries; e.g.
that is whiter which is more free from admixture with black. Moreover,
apart from the rules given above, that has such and such a character
in greater degree which admits in a greater degree of the definition
proper to the given character; e.g. if the definition of 'white' be 'a
colour which pierces the vision', then that is whiter which is in a
greater degree a colour that pierces the vision.

                                 6

  If the question be put in a particular and not in a universal
form, in the first place the universal constructive or destructive
commonplace rules that have been given may all be brought into use.
For in demolishing or establishing a thing universally we also show it
in particular: for if it be true of all, it is true also of some,
and if untrue of all, it is untrue of some. Especially handy and of
general application are the commonplace rules that are drawn from
the opposites and co-ordinates and inflexions of a thing: for public
opinion grants alike the claim that if all pleasure be good, then also
all pain is evil, and the claim that if some pleasure be good, then
also some pain is evil. Moreover, if some form of sensation be not a
capacity, then also some form of failure of sensation is not a failure
of capacity. Also, if the object of conception is in some cases an
object of knowledge, then also some form of conceiving is knowledge.
Again, if what is unjust be in some cases good, then also what is just
is in some cases evil; and if what happens justly is in some cases
evil, then also what happens unjustly is in some cases good. Also,
if what is pleasant is in some cases objectionable, then pleasure is
in some cases an objectionable thing. On the same principle, also,
if what is pleasant is in some cases beneficial, then pleasure is in
some cases a beneficial thing. The case is the same also as regards
the things that destroy, and the processes of generation and
destruction. For if anything that destroys pleasure or knowledge be in
some cases good, then we may take it that pleasure or knowledge is
in some cases an evil thing. Likewise, also, if the destruction of
knowledge be in some cases a good thing or its production an evil
thing, then knowledge will be in some cases an evil thing; e.g. if for
a man to forget his disgraceful conduct be a good thing, and to
remember it be an evil thing, then the knowledge of his disgraceful
conduct may be taken to be an evil thing. The same holds also in other
cases: in all such cases the premiss and the conclusion are equally
likely to be accepted.
  Moreover you should judge by means of greater or smaller or like
degrees: for if some member of another genus exhibit such and such a
character in a more marked degree than your object, while no member of
that genus exhibits that character at all, then you may take it that
neither does the object in question exhibit it; e.g. if some form of
knowledge be good in a greater degree than pleasure, while no form
of knowledge is good, then you may take it that pleasure is not good
either. Also, you should judge by a smaller or like degree in the same
way: for so you will find it possible both to demolish and to
establish a view, except that whereas both are possible by means of
like degrees, by means of a smaller degree it is possible only to
establish, not to overthrow. For if a certain form of capacity be good
in a like degree to knowledge, and a certain form of capacity be good,
then so also is knowledge; while if no form of capacity be good,
then neither is knowledge. If, too, a certain form of capacity be good
in a less degree than knowledge, and a certain form of capacity be
good, then so also is knowledge; but if no form of capacity be good,
there is no necessity that no form of knowledge either should be good.
Clearly, then, it is only possible to establish a view by means of a
less degree.
  Not only by means of another genus can you overthrow a view, but
also by means of the same, if you take the most marked instance of the
character in question; e.g. if it be maintained that some form of
knowledge is good, then, suppose it to be shown that prudence is not
good, neither will any other kind be good, seeing that not even the
kind upon which there is most general agreement is so. Moreover, you
should go to work by means of an hypothesis; you should claim that the
attribute, if it belongs or does not belong in one case, does so in
a like degree in all, e.g. that if the soul of man be immortal, so are
other souls as well, while if this one be not so, neither are the
others. If, then, it be maintained that in some instance the attribute
belongs, you must show that in some instance it does not belong: for
then it will follow, by reason of the hypothesis, that it does not
belong to any instance at all. If, on the other hand, it be maintained
that it does not belong in some instance, you must show that it does
belong in some instance, for in this way it will follow that it
belongs to all instances. It is clear that the maker of the hypothesis
universalizes the question, whereas it was stated in a particular
form: for he claims that the maker of a particular admission should
make a universal admission, inasmuch as he claims that if the
attribute belongs in one instance, it belongs also in all instances
alike.
  If the problem be indefinite, it is possible to overthrow a
statement in only one way; e.g. if a man has asserted that pleasure is
good or is not good, without any further definition. For if he meant
that a particular pleasure is good, you must show universally that
no pleasure is good, if the proposition in question is to be
demolished. And likewise, also, if he meant that some particular
pleasure is not good you must show universally that all pleasure is
good: it is impossible to demolish it in any other way. For if we show
that some particular pleasure is not good or is good, the
proposition in question is not yet demolished. It is clear, then, that
it is possible to demolish an indefinite statement in one way only,
whereas it can be established in two ways: for whether we show
universally that all pleasure is good, or whether we show that a
particular pleasure is good, the proposition in question will have
been proved. Likewise, also, supposing we are required to argue that
some particular pleasure is not good, if we show that no pleasure is
good or that a particular pleasure is not good, we shall have produced
an argument in both ways, both universally and in particular, to
show that some particular pleasure is not good. If, on the other hand,
the statement made be definite, it will be possible to demolish it
in two ways; e.g. if it be maintained that it is an attribute of
some particular pleasure to be good, while of some it is not: for
whether it be shown that all pleasure, or that no pleasure, is good,
the proposition in question will have been demolished. If, however, he
has stated that only one single pleasure is good, it is possible to
demolish it in three ways: for by showing that all pleasure, or that
no pleasure, or that more than one pleasure, is good, we shall have
demolished the statement in question. If the statement be made still
more definite, e.g. that prudence alone of the virtues is knowledge,
there are four ways of demolishing it: for if it be shown that all
virtue is knowledge, or that no virtue is so, or that some other
virtue (e.g. justice) is so, or that prudence itself is not knowledge,
the proposition in question will have been demolished.
  It is useful also to take a look at individual instances, in cases
where some attribute has been said to belong or not to belong, as in
the case of universal questions. Moreover, you should take a glance
among genera, dividing them by their species until you come to those
that are not further divisible, as has been said before:' for
whether the attribute is found to belong in all cases or in none,
you should, after adducing several instances, claim that he should
either admit your point universally, or else bring an objection
showing in what case it does not hold. Moreover, in cases where it
is possible to make the accident definite either specifically or
numerically, you should look and see whether perhaps none of them
belongs, showing e.g. that time is not moved, nor yet a movement, by
enumerating how many species there are of movement: for if none of
these belong to time, clearly it does not move, nor yet is a movement.
Likewise, also, you can show that the soul is not a number, by
dividing all numbers into either odd or even: for then, if the soul be
neither odd nor even, clearly it is not a number.
    In regard then to Accident, you should set to work by means like
these, and in this manner.

                              Book IV
                                 1

  NEXT we must go on to examine questions relating to Genus and
Property. These are elements in the questions that relate to
definitions, but dialecticians seldom address their inquiries to these
by themselves. If, then, a genus be suggested for something that is,
first take a look at all objects which belong to the same genus as the
thing mentioned, and see whether the genus suggested is not predicated
of one of them, as happens in the case of an accident: e.g. if
'good' be laid down to be the genus of 'pleasure', see whether some
particular pleasure be not good: for, if so, clearly good' is not
the genus of pleasure: for the genus is predicated of all the
members of the same species. Secondly, see whether it be predicated
not in the category of essence, but as an accident, as 'white' is
predicated of 'snow', or 'self-moved' of the soul. For 'snow' is not a
kind of 'white', and therefore 'white' is not the genus of snow, nor
is the soul a kind of 'moving object': its motion is an accident of
it, as it often is of an animal to walk or to be walking. Moreover,
'moving' does not seem to indicate the essence, but rather a state
of doing or of having something done to it. Likewise, also, 'white':
for it indicates not the essence of snow, but a certain quality of it.
So that neither of them is predicated in the category of 'essence'.
  Especially you should take a look at the definition of Accident, and
see whether it fits the genus mentioned, as (e.g.) is also the case in
the instances just given. For it is possible for a thing to be and not
to be self-moved, and likewise, also, for it to be and not to be
white. So that neither of these attributes is the genus but an
accident, since we were saying that an accident is an attribute
which can belong to a thing and also not belong.
  Moreover, see whether the genus and the species be not found in
the same division, but the one be a substance while the other is a
quality, or the one be a relative while the other is a quality, as
(e.g.) 'slow' and 'swan' are each a substance, while 'white' is not
a substance but a quality, so that 'white' is not the genus either
of 'snow' or of 'swan'. Again, knowledge' is a relative, while
'good' and 'noble' are each a quality, so that good, or noble, is
not the genus of knowledge. For the genera of relatives ought
themselves also to be relatives, as is the case with 'double': for
multiple', which is the genus of 'double', is itself also a
relative. To speak generally, the genus ought to fall under the same
division as the species: for if the species be a substance, so too
should be the genus, and if the species be a quality, so too the genus
should be a quality; e.g. if white be a quality, so too should
colour be. Likewise, also, in other cases.
  Again, see whether it be necessary or possible for the genus to
partake of the object which has been placed in the genus. 'To partake'
is defined as 'to admit the definition of that which is partaken.
Clearly, therefore, the species partake of the genera, but not the
genera of the species: for the species admits the definition of the
genus, whereas the genus does not admit that of the species. You
must look, therefore, and see whether the genus rendered partakes or
can possibly partake of the species, e.g. if any one were to render
anything as genus of 'being' or of 'unity': for then the result will
be that the genus partakes of the species: for of everything that
is, 'being' and 'unity' are predicated, and therefore their definition
as well.
  Moreover, see if there be anything of which the species rendered
is true, while the genus is not so, e.g. supposing 'being' or
'object of knowledge' were stated to be the genus of 'object of
opinion'. For 'object of opinion' will be a predicate of what does not
exist; for many things which do not exist are objects of opinion;
whereas that 'being' or 'object of knowledge' is not predicated of
what does not exist is clear. So that neither 'being' nor 'object of
knowledge' is the genus of 'object of opinion': for of the objects
of which the species is predicated, the genus ought to be predicated
as well.
  Again, see whether the object placed in the genus be quite unable to
partake of any of its species: for it is impossible that it should
partake of the genus if it do not partake of any of its species,
except it be one of the species reached by the first division: these
do partake of the genus alone. If, therefore, 'Motion' be stated as
the genus of pleasure, you should look and see if pleasure be
neither locomotion nor alteration, nor any of the rest of the given
modes of motion: for clearly you may then take it that it does not
partake of any of the species, and therefore not of the genus
either, since what partakes of the genus must necessarily partake of
one of the species as well: so that pleasure could not be a species of
Motion, nor yet be one of the individual phenomena comprised under the
term 'motion'. For individuals as well partake in the genus and the
species, as (e.g.) an individual man partakes of both 'man' and
'animal'.
  Moreover, see if the term placed in the genus has a wider denotation
than the genus, as (e.g.) 'object of opinion' has, as compared with
'being': for both what is and what is not are objects of opinion, so
that 'object of opinion' could not be a species of being: for the
genus is always of wider denotation than the species. Again, see if
the species and its genus have an equal denotation; suppose, for
instance, that of the attributes which go with everything, one were to
be stated as a species and the other as its genus, as for example
Being and Unity: for everything has being and unity, so that neither
is the genus of the other, since their denotation is equal.
Likewise, also, if the 'first' of a series and the 'beginning' were to
be placed one under the other: for the beginning is first and the
first is the beginning, so that either both expressions are
identical or at any rate neither is the genus of the other. The
elementary principle in regard to all such cases is that the genus has
a wider denotation than the species and its differentia: for the
differentia as well has a narrower denotation than the genus.
  See also whether the genus mentioned fails, or might be generally
thought to fail, to apply to some object which is not specifically
different from the thing in question; or, if your argument be
constructive, whether it does so apply. For all things that are not
specifically different have the same genus. If, therefore, it be shown
to apply to one, then clearly it applies to all, and if it fails to
apply to one, clearly it fails to apply to any; e.g. if any one who
assumes 'indivisible lines' were to say that the 'indivisible' is
their genus. For the aforesaid term is not the genus of divisible
lines, and these do not differ as regards their species from
indivisible: for straight lines are never different from each other as
regards their species.

                                 2

  Look and see, also, if there be any other genus of the given species
which neither embraces the genus rendered nor yet falls under it, e.g.
suppose any one were to lay down that 'knowledge' is the genus of
justice. For virtue is its genus as well, and neither of these
genera embraces the remaining one, so that knowledge could not be
the genus of justice: for it is generally accepted that whenever one
species falls under two genera, the one is embraced by the other.
Yet a principle of this kind gives rise to a difficulty in some cases.
For some people hold that prudence is both virtue and knowledge, and
that neither of its genera is embraced by the other: although
certainly not everybody admits that prudence is knowledge. If,
however, any one were to admit the truth of this assertion, yet it
would still be generally agreed to be necessary that the genera of the
same object must at any rate be subordinate either the one to the
other or both to the same, as actually is the case with virtue and
knowledge. For both fall under the same genus; for each of them is a
state and a disposition. You should look, therefore, and see whether
neither of these things is true of the genus rendered; for if the
genera be subordinate neither the one to the other nor both to the
same, then what is rendered could not be the true genus.
  Look, also, at the genus of the genus rendered, and so continually
at the next higher genus, and see whether all are predicated of the
species, and predicated in the category of essence: for all the higher
genera should be predicated of the species in the category of essence.
If, then, there be anywhere a discrepancy, clearly what is rendered is
not the true genus. [Again, see whether either the genus itself, or
one of its higher genera, partakes of the species: for the higher
genus does not partake of any of the lower.] If, then, you are
overthrowing a view, follow the rule as given: if establishing one,
then-suppose that what has been named as genus be admitted to belong
to the species, only it be disputed whether it belongs as genus-it
is enough to show that one of its higher genera is predicated of the
species in the category of essence. For if one of them be predicated
in the category of essence, all of them, both higher and lower than
this one, if predicated at all of the species, will be predicated of
it in the category of essence: so that what has been rendered as genus
is also predicated in the category of essence. The premiss that when
one genus is predicated in the category of essence, all the rest, if
predicated at all, will be predicated in the category of essence,
should be secured by induction. Supposing, however, that it be
disputed whether what has been rendered as genus belongs at all, it is
not enough to show that one of the higher genera is predicated of
the species in the category of essence: e.g. if any one has rendered
'locomotion' as the genus of walking, it is not enough to show that
walking is 'motion' in order to show that it is 'locomotion', seeing
that there are other forms of motion as well; but one must show in
addition that walking does not partake of any of the species of motion
produced by the same division except locomotion. For of necessity what
partakes of the genus partakes also of one of the species produced
by the first division of the genus. If, therefore, walking does not
partake either of increase or decrease or of the other kinds of
motion, clearly it would partake of locomotion, so that locomotion
would be the genus of walking.
  Again, look among the things of which the given species is
predicated as genus, and see if what is rendered as its genus be
also predicated in the category of essence of the very things of which
the species is so predicated, and likewise if all the genera higher
than this genus are so predicated as well. For if there be anywhere
a discrepancy, clearly what has been rendered is not the true genus:
for had it been the genus, then both the genera higher than it, and it
itself, would all have been predicated in the category of essence of
those objects of which the species too is predicated in the category
of essence. If, then, you are overthrowing a view, it is useful to see
whether the genus fails to be predicated in the category of essence of
those things of which the species too is predicated. If establishing a
view, it is useful to see whether it is predicated in the category
of essence: for if so, the result will be that the genus and the
species will be predicated of the same object in the category of
essence, so that the same object falls under two genera: the genera
must therefore of necessity be subordinate one to the other, and
therefore if it be shown that the one we wish to establish as genus is
not subordinate to the species, clearly the species would be
subordinate to it, so that you may take it as shown that it is the
genus.
  Look, also, at the definitions of the genera, and see whether they
apply both to the given species and to the objects which partake of
the species. For of necessity the definitions of its genera must be
predicated of the species and of the objects which partake of the
species: if, then, there be anywhere a discrepancy, clearly what has
been rendered is not the genus.
  Again, see if he has rendered the differentia as the genus, e.g.
'immortal' as the genus of 'God'. For 'immortal' is a differentia of
'living being', seeing that of living beings some are mortal and
others immortal. Clearly, then, a bad mistake has been made; for the
differentia of a thing is never its genus. And that this is true is
clear: for a thing's differentia never signifies its essence, but
rather some quality, as do 'walking' and 'biped'.
  Also, see whether he has placed the differentia inside the genus,
e.g. by taking 'odd' as a number'. For 'odd' is a differentia of
number, not a species. Nor is the differentia generally thought to
partake of the genus: for what partakes of the genus is always
either a species or an individual, whereas the differentia is
neither a species nor an individual. Clearly, therefore, the
differentia does not partake of the genus, so that 'odd' too is no
species but a differentia, seeing that it does not partake of the
genus.
  Moreover, see whether he has placed the genus inside the species,
e.g. by taking 'contact' to be a 'juncture', or 'mixture' a
'fusion', or, as in Plato's definition,' 'locomotion' to be the same
as 'carriage'. For there is no necessity that contact should be
juncture: rather, conversely, juncture must be contact: for what is in
contact is not always joined, though what is joined is always in
contact. Likewise, also, in the remaining instances: for mixture is
not always a 'fusion' (for to mix dry things does not fuse them),
nor is locomotion always 'carriage'. For walking is not generally
thought to be carriage: for 'carriage' is mostly used of things that
change one place for another involuntarily, as happens in the case
of inanimate things. Clearly, also, the species, in the instances
given, has a wider denotation than the genus, whereas it ought to be
vice versa.
 Again, see whether he has placed the differentia inside the
species, by taking (e.g.) 'immortal' to be 'a god'. For the result
will be that the species has an equal or wider denotation: and this
cannot be, for always the differentia has an equal or a wider
denotation than the species. Moreover, see whether he has placed the
genus inside the differentia, by making 'colour' (e.g.) to be a
thing that 'pierces', or 'number' a thing that is 'odd'. Also, see
if he has mentioned the genus as differentia: for it is possible for a
man to bring forward a statement of this kind as well, e.g. that
'mixture' is the differentia of 'fusion', or that change of place'
is the differentia of 'carriage'. All such cases should be examined by
means of the same principles: for they depend upon common rules: for
the genus should have a wider denotation that its differentia, and
also should not partake of its differentia; whereas, if it be rendered
in this manner, neither of the aforesaid requirements can be
satisfied: for the genus will both have a narrower denotation than its
differentia, and will partake of it.
  Again, if no differentia belonging to the genus be predicated of the
given species, neither will the genus be predicated of it; e.g. of
'soul' neither 'odd' nor 'even' is predicated: neither therefore is
'number'. Moreover, see whether the species is naturally prior and
abolishes the genus along with itself: for the contrary is the general
view. Moreover, if it be possible for the genus stated, or for its
differentia, to be absent from the alleged species, e.g. for
'movement' to be absent from the 'soul', or 'truth and falsehood' from
'opinion', then neither of the terms stated could be its genus or
its differentia: for the general view is that the genus and the
differentia accompany the species, as long as it exists.

                                 3

  Look and see, also, if what is placed in the genus partakes or could
possibly partake of any contrary of the genus: for in that case the
same thing will at the same time partake of contrary things, seeing
that the genus is never absent from it, while it partakes, or can
possibly partake, of the contrary genus as well. Moreover, see whether
the species shares in any character which it is utterly impossible for
any member of the genus to have. Thus (e.g.) if the soul has a share
in life, while it is impossible for any number to live, then the
soul could not be a species of number.
  You should look and see, also, if the species be a homonym of the
genus, and employ as your elementary principles those already stated
for dealing with homonymity: for the genus and the species are
synonymous.
  Seeing that of every genus there is more than one species, look
and see if it be impossible that there should be another species
than the given one belonging to the genus stated: for if there
should be none, then clearly what has been stated could not be a genus
at all.
  Look and see, also, if he has rendered as genus a metaphorical
expression, describing (e.g. 'temperance' as a 'harmony': a 'harmony':
for a genus is always predicated of its species in its literal
sense, whereas 'harmony' is predicated of temperance not in a
literal sense but metaphorically: for a harmony always consists in
notes.
  Moreover, if there be any contrary of the species, examine it. The
examination may take different forms; first of all see if the contrary
as well be found in the same genus as the species, supposing the genus
to have no contrary; for contraries ought to be found in the same
genus, if there be no contrary to the genus. Supposing, on the other
hand, that there is a contrary to the genus, see if the contrary of
the species be found in the contrary genus: for of necessity the
contrary species must be in the contrary genus, if there be any
contrary to the genus. Each of these points is made plain by means
of induction. Again, see whether the contrary of the species be not
found in any genus at all, but be itself a genus, e.g. 'good': for
if this be not found in any genus, neither will its contrary be
found in any genus, but will itself be a genus, as happens in the case
of 'good' and 'evil': for neither of these is found in a genus, but
each of them is a genus. Moreover, see if both genus and species be
contrary to something, and one pair of contraries have an
intermediary, but not the other. For if the genera have an
intermediary, so should their species as well, and if the species
have, so should their genera as well, as is the case with (1) virtue
and vice and (2) justice and injustice: for each pair has an
intermediary. An objection to this is that there is no intermediary
between health and disease, although there is one between evil and
good. Or see whether, though there be indeed an intermediary between
both pairs, i.e. both between the species and between the genera,
yet it be not similarly related, but in one case be a mere negation of
the extremes, whereas in the other case it is a subject. For the
general view is that the relation should be similar in both cases,
as it is in the cases of virtue and vice and of justice and injustice:
for the intermediaries between both are mere negations. Moreover,
whenever the genus has no contrary, look and see not merely whether
the contrary of the species be found in the same genus, but the
intermediate as well: for the genus containing the extremes contains
the intermediates as well, as (e.g.) in the case of white and black:
for 'colour' is the genus both of these and of all the intermediate
colours as well. An objection may be raised that 'defect' and 'excess'
are found in the same genus (for both are in the genus 'evil'),
whereas moderate amount', the intermediate between them, is found
not in 'evil' but in 'good'. Look and see also whether, while the
genus has a contrary, the species has none; for if the genus be
contrary to anything, so too is the species, as virtue to vice and
justice to injustice.
  Likewise. also, if one were to look at other instances, one would
come to see clearly a fact like this. An objection may be raised in
the case of health and disease: for health in general is the
contrary of disease, whereas a particular disease, being a species
of disease, e.g. fever and ophthalmia and any other particular
disease, has no contrary.
  If, therefore, you are demolishing a view, there are all these
ways in which you should make your examination: for if the aforesaid
characters do not belong to it, clearly what has been rendered is
not the genus. If, on the other hand, you are establishing a view,
there are three ways: in the first place, see whether the contrary
of the species be found in the genus stated, suppose the genus have no
contrary: for if the contrary be found in it, clearly the species in
question is found in it as well. Moreover, see if the intermediate
species is found in the genus stated: for whatever genus contains
the intermediate contains the extremes as well. Again, if the genus
have a contrary, look and see whether also the contrary species is
found in the contrary genus: for if so, clearly also the species in
question is found in the genus in question.
  Again, consider in the case of the inflexions and the co-ordinates
of species and genus, and see whether they follow likewise, both in
demolishing and in establishing a view. For whatever attribute belongs
or does not belong to one belongs or does not belong at the same
time to all; e.g. if justice be a particular form of knowledge, then
also 'justly' is 'knowingly' and the just man is a man of knowledge:
whereas if any of these things be not so, then neither is any of the
rest of them.

                                 4

  Again, consider the case of things that bear a like relation to
one another. Thus (e.g.) the relation of the pleasant to pleasure is
like that of the useful to the good: for in each case the one produces
the other. If therefore pleasure be a kind of 'good', then also the
pleasant will be a kind of 'useful': for clearly it may be taken to be
productive of good, seeing that pleasure is good. In the same way also
consider the case of processes of generation and destruction; if
(e.g.) to build be to be active, then to have built is to have been
active, and if to learn be to recollect, then also to have learnt is
to have recollected, and if to be decomposed be to be destroyed,
then to have been decomposed is to have been destroyed, and
decomposition is a kind of destruction. Consider also in the same
way the case of things that generate or destroy, and of the capacities
and uses of things; and in general, both in demolishing and in
establishing an argument, you should examine things in the light of
any resemblance of whatever description, as we were saying in the case
of generation and destruction. For if what tends to destroy tends to
decompose, then also to be destroyed is to be decomposed: and if
what tends to generate tends to produce, then to be generated is to be
produced, and generation is production. Likewise, also, in the case of
the capacities and uses of things: for if a capacity be a disposition,
then also to be capable of something is to be disposed to it, and if
the use of anything be an activity, then to use it is to be active,
and to have used it is to have been active.
  If the opposite of the species be a privation, there are two ways of
demolishing an argument, first of all by looking to see if the
opposite be found in the genus rendered: for either the privation is
to be found absolutely nowhere in the same genus, or at least not in
the same ultimate genus: e.g. if the ultimate genus containing sight
be sensation, then blindness will not be a sensation. Secondly, if
there be a sensation. Secondly, if there be a privation opposed to
both genus and species, but the opposite of the species be not found
in the opposite of the genus, then neither could the species
rendered be in the genus rendered. If, then, you are demolishing a
view, you should follow the rule as stated; but if establishing one
there is but one way: for if the opposite species be found in the
opposite genus, then also the species in question would be found in
the genus in question: e.g. if 'blindness' be a form of
'insensibility', then 'sight' is a form of 'sensation'.
  Again, look at the negations of the genus and species and convert
the order of terms, according to the method described in the case of
Accident: e.g. if the pleasant be a kind of good, what is not good
is not pleasant. For were this no something not good as well would
then be pleasant. That, however, cannot be, for it is impossible, if
'good' be the genus of pleasant, that anything not good should be
pleasant: for of things of which the genus is not predicated, none
of the species is predicated either. Also, in establishing a view, you
should adopt the same method of examination: for if what is not good
be not pleasant, then what is pleasant is good, so that 'good' is
the genus of 'pleasant'.
  If the species be a relative term, see whether the genus be a
relative term as well: for if the species be a relative term, so too
is the genus, as is the case with 'double' and 'multiple': for each is
a relative term. If, on the other hand, the genus be a relative
term, there is no necessity that the species should be so as well: for
'knowledge'is a relative term, but not so 'grammar'. Or possibly not
even the first statement would be generally considered true: for
virtue is a kind of 'noble' and a kind of 'good' thing, and yet, while
'virtue' is a relative term, 'good' and 'noble' are not relatives
but qualities. Again, see whether the species fails to be used in
the same relation when called by its own name, and when called by
the name of its genus: e.g. if the term 'double' be used to mean the
double of a 'half', then also the term 'multiple' ought to be used
to mean multiple of a 'half'. Otherwise 'multiple' could not be the
genus of 'double'.
  Moreover, see whether the term fail to be used in the same
relation both when called by the name of its genus, and also when
called by those of all the genera of its genus. For if the double be a
multiple of a half, then 'in excess of 'will also be used in
relation to a 'half': and, in general, the double will be called by
the names of all the higher genera in relation to a 'half'. An
objection may be raised that there is no necessity for a term to be
used in the same relation when called by its own name and when
called by that of its genus: for 'knowledge' is called knowledge 'of
an object', whereas it is called a 'state' and 'disposition' not of an
'object' but of the 'soul'.
  Again, see whether the genus and the species be used in the same way
in respect of the inflexions they take, e.g. datives and genitives and
all the rest. For as the species is used, so should the genus be as
well, as in the case of 'double' and its higher genera: for we say
both 'double of' and 'multiple of' a thing. Likewise, also, in the
case of 'knowledge': for both knowledge' itself and its genera, e.g.
'disposition' and 'state', are said to be 'of' something. An objection
may be raised that in some cases it is not so: for we say 'superior
to' and 'contrary to' so and so, whereas 'other', which is the genus
of these terms, demands not 'to' but 'than': for the expression is
'other than' so and so.
  Again, see whether terms used in like case relationships fail to
yield a like construction when converted, as do 'double' and
'multiple'. For each of these terms takes a genitive both in itself
and in its converted form: for we say both a half of' and 'a
fraction of' something. The case is the same also as regards both
'knowledge' and 'conception': for these take a genitive, and by
conversion an 'object of knowledge' and an 'object of conception'
are both alike used with a dative. If, then, in any cases the
constructions after conversion be not alike, clearly the one term is
not the genus of the other.
  Again, see whether the species and the genus fail to be used in
relation to an equal number of things: for the general view is that
the uses of both are alike and equal in number, as is the case with
'present' and 'grant'. For a present' is of something or to some
one, and also a 'grant' is of something and to some one: and 'grant'
is the genus of 'present', for a 'present' is a 'grant that need not
be returned'. In some cases, however, the number of relations in which
the terms are used happens not to be equal, for while 'double' is
double of something, we speak of 'in excess' or 'greater' in
something, as well as of or than something: for what is in excess or
greater is always in excess in something, as well as in excess of
something. Hence the terms in question are not the genera of 'double',
inasmuch as they are not used in relation to an equal number of things
with the species. Or possibly it is not universally true that
species and genus are used in relation to an equal number of things.
  See, also, if the opposite of the species have the opposite of the
genus as its genus, e.g. whether, if 'multiple' be the genus of
'double', 'fraction' be also the genus of 'half'. For the opposite
of the genus should always be the genus of the opposite species. If,
then, any one were to assert that knowledge is a kind of sensation,
then also the object of knowledge will have to be a kind of object
of sensation, whereas it is not: for an object of knowledge is not
always an object of sensation: for objects of knowledge include some
of the objects of intuition as well. Hence 'object of sensation' is
not the genus of 'object of knowledge': and if this be so, neither
is 'sensation' the genus of 'knowledge'.
  Seeing that of relative terms some are of necessity found in, or
used of, the things in relation to which they happen at any time to be
used (e.g. 'disposition' and 'state' and 'balance'; for in nothing
else can the aforesaid terms possibly be found except in the things in
relation to which they are used), while others need not be found in
the things in relation to which they are used at any time, though they
still may be (e.g. if the term 'object of knowledge' be applied to the
soul: for it is quite possible that the knowledge of itself should
be possessed by the soul itself, but it is not necessary, for it is
possible for this same knowledge to be found in some one else),
while for others, again, it is absolutely impossible that they
should be found in the things in relation to which they happen at
any time to be used (as e.g. that the contrary should be found in
the contrary or knowledge in the object of knowledge, unless the
object of knowledge happen to be a soul or a man)-you should look,
therefore, and see whether he places a term of one kind inside a genus
that is not of that kind, e.g. suppose he has said that 'memory' is
the 'abiding of knowledge'. For 'abiding' is always found in that
which abides, and is used of that, so that the abiding of knowledge
also will be found in knowledge. Memory, then, is found in
knowledge, seeing that it is the abiding of knowledge. But this is
impossible, for memory is always found in the soul. The aforesaid
commonplace rule is common to the subject of Accident as well: for
it is all the same to say that 'abiding' is the genus of memory, or to
allege that it is an accident of it. For if in any way whatever memory
be the abiding of knowledge, the same argument in regard to it will
apply.
                                 5

  Again, see if he has placed what is a 'state' inside the genus
'activity', or an activity inside the genus 'state', e.g. by
defining 'sensation' as 'movement communicated through the body':
for sensation is a 'state', whereas movement is an 'activity'.
Likewise, also, if he has said that memory is a 'state that is
retentive of a conception', for memory is never a state, but rather an
activity.
  They also make a bad mistake who rank a 'state' within the
'capacity' that attends it, e.g. by defining 'good temper' as the
'control of anger', and 'courage' and 'justice' as 'control of
fears' and of 'gains': for the terms 'courageous' and
'good-tempered' are applied to a man who is immune from passion,
whereas 'self-controlled' describes the man who is exposed to
passion and not led by it. Quite possibly, indeed, each of the
former is attended by a capacity such that, if he were exposed to
passion, he would control it and not be led by it: but, for all
that, this is not what is meant by being 'courageous' in the one case,
and 'good tempered' in the other; what is meant is an absolute
immunity from any passions of that kind at all.
  Sometimes, also, people state any kind of attendant feature as the
genus, e.g. 'pain' as the genus of 'anger' and 'conception' as that of
conviction'. For both of the things in question follow in a certain
sense upon the given species, but neither of them is genus to it.
For when the angry man feels pain, the pain bas appeared in him
earlier than the anger: for his anger is not the cause of his pain,
but his pain of his anger, so that anger emphatically is not pain.
By the same reasoning, neither is conviction conception: for it is
possible to have the same conception even without being convinced of
it, whereas this is impossible if conviction be a species of
conception: for it is impossible for a thing still to remain the
same if it be entirely transferred out of its species, just as neither
could the same animal at one time be, and at another not be, a man.
If, on the other hand, any one says that a man who has a conception
must of necessity be also convinced of it, then 'conception' and
'conviction' will be used with an equal denotation, so that not even
so could the former be the genus of the latter: for the denotation
of the genus should be wider.
  See, also, whether both naturally come to be anywhere in the same
thing: for what contains the species contains the genus as well:
e.g. what contains 'white' contains 'colour' as well, and what
contains 'knowledge of grammar' contains 'knowledge' as well. If,
therefore, any one says that 'shame' is 'fear', or that 'anger' is
'pain', the result will be that genus and species are not found in the
same thing: for shame is found in the 'reasoning' faculty, whereas
fear is in the 'spirited' faculty, and 'pain' is found in the
faculty of 'desires'. (for in this pleasure also is found), whereas
'anger' is found in the 'spirited' faculty. Hence the terms rendered
are not the genera, seeing that they do not naturally come to be in
the same faculty as the species. Likewise, also, if 'friendship' be
found in the faculty of desires, you may take it that it is not a form
of 'wishing': for wishing is always found in the 'reasoning'
faculty. This commonplace rule is useful also in dealing with
Accident: for the accident and that of which it is an accident are
both found in the same thing, so that if they do not appear in the
same thing, clearly it is not an accident.
  Again, see if the species partakes of the genus attributed only in
some particular respect: for it is the general view that the genus
is not thus imparted only in some particular respect: for a man is not
an animal in a particular respect, nor is grammar knowledge in a
particular respect only. Likewise also in other instances. Look,
therefore, and see if in the case of any of its species the genus be
imparted only in a certain respect; e.g. if 'animal' has been
described as an 'object of perception' or of 'sight'. For an animal is
an object of perception or of sight in a particular respect only;
for it is in respect of its body that it is perceived and seen, not in
respect of its soul, so that-'object of sight' and 'object of
perception' could not be the genus of 'animal'.
  Sometimes also people place the whole inside the part without
detection, defining (e.g.) 'animal' as an 'animate body'; whereas
the part is not predicated in any sense of the whole, so that 'body'
could not be the genus of animal, seeing that it is a part.
  See also if he has put anything that is blameworthy or objectionable
into the class 'capacity' or 'capable', e.g. by defining a 'sophist'
or a 'slanderer', or a 'thief' as 'one who is capable of secretly
thieving other people's property'. For none of the aforesaid
characters is so called because he is 'capable' in one of these
respects: for even God and the good man are capable of doing bad
things, but that is not their character: for it is always in respect
of their choice that bad men are so called. Moreover, a capacity is
always a desirable thing: for even the capacities for doing bad things
are desirable, and therefore it is we say that even God and the good
man possess them; for they are capable (we say) of doing evil. So then
'capacity' can never be the genus of anything blameworthy. Else, the
result will be that what is blameworthy is sometimes desirable: for
there will be a certain form of capacity that is blameworthy.
  Also, see if he has put anything that is precious or desirable for
its own sake into the class 'capacity' or 'capable' or 'productive' of
anything. For capacity, and what is capable or productive of anything,
is always desirable for the sake of something else.
  Or see if he has put anything that exists in two genera or more into
one of them only. For some things it is impossible to place in a
single genus, e.g. the 'cheat' and the 'slanderer': for neither he who
has the will without the capacity, nor he who has the capacity without
the will, is a slanderer or cheat, but he who has both of them.
Hence he must be put not into one genus, but into both the aforesaid
genera.
  Moreover, people sometimes in converse order render genus as
differentia, and differentia as genus, defining (e.g.) astonishment as
'excess of wonderment' and conviction as 'vehemence of conception'.
For neither 'excess' nor 'vehemence' is the genus, but the
differentia: for astonishment is usually taken to be an 'excessive
wonderment', and conviction to be a 'vehement conception', so that
'wonderment' and 'conception' are the genus, while 'excess' and
'vehemence' are the differentia. Moreover, if any one renders 'excess'
and 'vehemence' as genera, then inanimate things will be convinced and
astonished. For 'vehemence' and 'excess' of a thing are found in a
thing which is thus vehement and in excess. If, therefore,
astonishment be excess of wonderment the astonishment will be found in
the wonderment, so that 'wonderment' will be astonished! Likewise,
also, conviction will be found in the conception, if it be
'vehemence of conception', so that the conception will be convinced.
Moreover, a man who renders an answer in this style will in
consequence find himself calling vehemence vehement and excess
excessive: for there is such a thing as a vehement conviction: if then
conviction be 'vehemence', there would be a 'vehement vehemence'.
Likewise, also, there is such a thing as excessive astonishment: if
then astonishment be an excess, there would be an 'excessive
excess'. Whereas neither of these things is generally believed, any
more than that knowledge is a knower or motion a moving thing.
  Sometimes, too, people make the bad mistake of putting an
affection into that which is affected, as its genus, e.g. those who
say that immortality is everlasting life: for immortality seems to
be a certain affection or accidental feature of life. That this saying
is true would appear clear if any one were to admit that a man can
pass from being mortal and become immortal: for no one will assert
that he takes another life, but that a certain accidental feature or
affection enters into this one as it is. So then 'life' is not the
genus of immortality.
  Again, see if to an affection he has ascribed as genus the object of
which it is an affection, by defining (e.g.) wind as 'air in
motion'. Rather, wind is 'a movement of air': for the same air
persists both when it is in motion and when it is still. Hence wind is
not 'air' at all: for then there would also have been wind when the
air was not in motion, seeing that the same air which formed the
wind persists. Likewise, also, in other cases of the kind. Even, then,
if we ought in this instance to admit the point that wind is 'air in
motion', yet we should accept a definition of the kind, not about
all those things of which the genus is not true, but only in cases
where the genus rendered is a true predicate. For in some cases,
e.g. 'mud' or 'snow', it is not generally held to be true. For
people tell you that snow is 'frozen water' and mud is earth mixed
with moisture', whereas snow is not water, nor mud earth, so that
neither of the terms rendered could be the genus: for the genus should
be true of all its species. Likewise neither is wine 'fermented
water', as Empedocles speaks of 'water fermented in wood';' for it
simply is not water at all.

                                 6

  Moreover, see whether the term rendered fail to be the genus of
anything at all; for then clearly it also fails to be the genus of the
species mentioned. Examine the point by seeing whether the objects
that partake of the genus fail to be specifically different from one
another, e.g. white objects: for these do not differ specifically from
one another, whereas of a genus the species are always different, so
that 'white' could not be the genus of anything.
  Again, see whether he has named as genus or differentia some feature
that goes with everything: for the number of attributes that follow
everything is comparatively large: thus (e.g.) 'Being' and 'Unity' are
among the number of attributes that follow everything. If,
therefore, he has rendered 'Being' as a genus, clearly it would be the
genus of everything, seeing that it is predicated of everything; for
the genus is never predicated of anything except of its species. Hence
Unity, inter alia, will be a species of Being. The result,
therefore, is that of all things of which the genus is predicated, the
species is predicated as well, seeing that Being and Unity are
predicates of absolutely everything, whereas the predication of the
species ought to be of narrower range. If, on the other hand, he has
named as differentia some attribute that follows everything, clearly
the denotation of the differentia will be equal to, or wider than,
that of the genus. For if the genus, too, be some attribute that
follows everything, the denotation of the differentia will be equal to
its denotation, while if the genus do not follow everything, it will
be still wider.
  Moreover, see if the description 'inherent in S' be used of the
genus rendered in relation to its species, as it is used of 'white' in
the case of snow, thus showing clearly that it could not be the genus:
for 'true of S' is the only description used of the genus in
relation to its species. Look and see also if the genus fails to be
synonymous with its species. For the genus is always predicated of its
species synonymously.
  Moreover, beware, whenever both species and genus have a contrary,
and he places the better of the contraries inside the worse genus: for
the result will be that the remaining species will be found in the
remaining genus, seeing that contraries are found in contrary
genera, so that the better species will be found in the worse genus
and the worse in the better: whereas the usual view is that of the
better species the genus too is better. Also see if he has placed
the species inside the worse and not inside the better genus, when
it is at the same time related in like manner to both, as (e.g.) if he
has defined the 'soul' as a 'form of motion' or 'a form of moving
thing'. For the same soul is usually thought to be a principle alike
of rest and of motion, so that, if rest is the better of the two, this
is the genus into which the soul should have been put.
  Moreover, judge by means of greater and less degrees: if
overthrowing a view, see whether the genus admits of a greater degree,
whereas neither the species itself does so, nor any term that is
called after it: e.g. if virtue admits of a greater degree, so too
does justice and the just man: for one man is called 'more just than
another'. If, therefore, the genus rendered admits of a greater
degree, whereas neither the species does so itself nor yet any term
called after it, then what has been rendered could not be the genus.
  Again, if what is more generally, or as generally, thought to be the
genus be not so, clearly neither is the genus rendered. The
commonplace rule in question is useful especially in cases where the
species appears to have several predicates in the category of essence,
and where no distinction has been drawn between them, and we cannot
say which of them is genus; e.g. both 'pain' and the 'conception of
a slight' are usually thought to be predicates of 'anger in the
category of essence: for the angry man is both in pain and also
conceives that he is slighted. The same mode of inquiry may be applied
also to the case of the species, by comparing it with some other
species: for if the one which is more generally, or as generally,
thought to be found in the genus rendered be not found therein, then
clearly neither could the species rendered be found therein.
  In demolishing a view, therefore, you should follow the rule as
stated. In establishing one, on the other hand, the commonplace rule
that you should see if both the genus rendered and the species admit
of a greater degree will not serve: for even though both admit it,
it is still possible for one not to be the genus of the other. For
both 'beautiful' and 'white' admit of a greater degree, and neither is
the genus of the other. On the other hand, the comparison of the
genera and of the species one with another is of use: e.g. supposing A
and B to have a like claim to be genus, then if one be a genus, so
also is the other. Likewise, also, if what has less claim be a
genus, so also is what has more claim: e.g. if 'capacity' have more
claim than 'virtue' to be the genus of self-control, and virtue be the
genus, so also is capacity. The same observations will apply also in
the case of the species. For instance, supposing A and B to have a
like claim to be a species of the genus in question, then if the one
be a species, so also is the other: and if that which is less
generally thought to be so be a species, so also is that which is more
generally thought to be so.
  Moreover, to establish a view, you should look and see if the
genus is predicated in the category of essence of those things of
which it has been rendered as the genus, supposing the species
rendered to be not one single species but several different ones:
for then clearly it will be the genus. If, on the other, the species
rendered be single, look and see whether the genus be predicated in
the category of essence of other species as well: for then, again, the
result will be that it is predicated of several different species.
  Since some people think that the differentia, too, is a predicate of
the various species in the category of essence, you should distinguish
the genus from the differentia by employing the aforesaid elementary
principles-(a) that the genus has a wider denotation than the
differentia; (b) that in rendering the essence of a thing it is more
fitting to state the genus than the differentia: for any one who
says that 'man' is an 'animal' shows what man is better than he who
describes him as 'walking'; also (c) that the differentia always
signifies a quality of the genus, whereas the genus does not do this
of the differentia: for he who says 'walking' describes an animal of a
certain quality, whereas he who says 'animal' describes an animal of a
certain quality, whereas he who says 'animal' does not describe a
walking thing of a certain quality.
  The differentia, then, should be distinguished from the genus in
this manner. Now seeing it is generally held that if what is
musical, in being musical, possesses knowledge in some respect, then
also 'music' is a particular kind of 'knowledge'; and also that if
what walks is moved in walking, then 'walking' is a particular kind of
'movement'; you should therefore examine in the aforesaid manner any
genus in which you want to establish the existence of something;
e.g. if you wish to prove that 'knowledge' is a form of
'conviction', see whether the knower in knowing is convinced: for then
clearly knowledge would be a particular kind of conviction. You should
proceed in the same way also in regard to the other cases of this
kind.
  Moreover, seeing that it is difficult to distinguish whatever always
follows along with a thing, and is not convertible with it, from its
genus, if A follows B universally, whereas B does not follow A
universally-as e.g. 'rest' always follows a 'calm' and
'divisibility' follows 'number', but not conversely (for the divisible
is not always a number, nor rest a calm)-you may yourself assume in
your treatment of them that the one which always follows is the genus,
whenever the other is not convertible with it: if, on the other
hand, some one else puts forward the proposition, do not accept it
universally. An objection to it is that 'not-being' always follows
what is 'coming to be' (for what is coming to be is not) and is not
convertible with it (for what is not is not always coming to be),
and that still 'not-being' is not the genus of 'coming to be': for
'not-being' has not any species at all. Questions, then, in regard
to Genus should be investigated in the ways described.

                              Book V
                                 1

  THE question whether the attribute stated is or is not a property,
should be examined by the following methods:
  Any 'property' rendered is always either essential and permanent
or relative and temporary: e.g. it is an 'essential property' of man
to be 'by nature a civilized animal': a 'relative property' is one
like that of the soul in relation to the body, viz. that the one is
fitted to command, and the other to obey: a 'permanent property' is
one like the property which belongs to God, of being an 'immortal
living being': a 'temporary property' is one like the property which
belongs to any particular man of walking in the gymnasium.
  [The rendering of a property 'relatively' gives rise either to two
problems or to four. For if he at the same time render this property
of one thing and deny it of another, only two problems arise, as in
the case of a statement that it is a property of a man, in relation to
a horse, to be a biped. For one might try both to show that a man is
not a biped, and also that a horse is a biped: in both ways the
property would be upset. If on the other hand he render one apiece
of two attributes to each of two things, and deny it in each case of
the other, there will then be four problems; as in the case of a
statement that it is a property of a man in relation to a horse for
the former to be a biped and the latter a quadruped. For then it is
possible to try to show both that a man is not naturally a biped,
and that he is a quadruped, and also that the horse both is a biped,
and is not a quadruped. If you show any of these at all, the
intended attribute is demolished.]
  An 'essential' property is one which is rendered of a thing in
comparison with everything else and distinguishes the said thing
from everything else, as does 'a mortal living being capable of
receiving knowledge' in the case of man. A 'relative' property is
one which separates its subject off not from everything else but
only from a particular definite thing, as does the property which
virtue possesses, in comparison with knowledge, viz. that the former
is naturally produced in more than one faculty, whereas the latter
is produced in that of reason alone, and in those who have a reasoning
faculty. A 'permanent' property is one which is true at every time,
and never fails, like being' compounded of soul and body', in the case
of a living creature. A 'temporary' property is one which is true at
some particular time, and does not of necessity always follow; as,
of some particular man, that he walks in the market-place.
  To render a property 'relatively' to something else means to state
the difference between them as it is found either universally and
always, or generally and in most cases: thus a difference that is
found universally and always, is one such as man possesses in
comparison with a horse, viz. being a biped: for a man is always and
in every case a biped, whereas a horse is never a biped at any time.
On the other hand, a difference that is found generally and in most
cases, is one such as the faculty of reason possesses in comparison
with that of desire and spirit, in that the former commands, while the
latter obeys: for the reasoning faculty does not always command, but
sometimes also is under command, nor is that of desire and spirit
always under command, but also on occasion assumes the command,
whenever the soul of a man is vicious.
  Of 'properties' the most 'arguable' are the essential and
permanent and the relative. For a relative property gives rise, as
we said before, to several questions: for of necessity the questions
arising are either two or four, or that arguments in regard to these
are several. An essential and a permanent property you can discuss
in relation to many things, or can observe in relation to many periods
of time: if essential', discuss it in comparison with many things: for
the property ought to belong to its subject in comparison with every
single thing that is, so that if the subject be not distinguished by
it in comparison with everything else, the property could not have
been rendered correctly. So a permanent property you should observe in
relation to many periods of time; for if it does not or did not, or is
not going to, belong, it will not be a property. On the other hand,
about a temporary property we do not inquire further than in regard to
the time called 'the present'; and so arguments in regard to it are
not many; whereas an arguable' question is one in regard to which it
is possible for arguments both numerous and good to arise.
  The so-called 'relative' property, then, should be examined by means
of the commonplace arguments relating to Accident, to see whether it
belongs to the one thing and not to the other: on the other hand,
permanent and essential properties should be considered by the
following methods.

                                 2

  First, see whether the property has or has not been rendered
correctly. Of a rendering being incorrect or correct, one test is to
see whether the terms in which the property is stated are not or are
more intelligible-for destructive purposes, whether they are not so,
and for constructive purposes, whether they are so. Of the terms not
being more intelligible, one test is to see whether the property which
he renders is altogether more unintelligible than the subject whose
property he has stated: for, if so, the property will not have been
stated correctly. For the object of getting a property constituted
is to be intelligible: the terms therefore in which it is rendered
should be more intelligible: for in that case it will be possible to
conceive it more adequately, e.g. any one who has stated that it is
a property of 'fire' to 'bear a very close resemblance to the soul',
uses the term 'soul', which is less intelligible than 'fire'-for we
know better what fire is than what soul is-, and therefore a 'very
close resemblance to the soul' could not be correctly stated to be a
property of fire. Another test is to see whether the attribution of
A (property) to B (subject) fails to be more intelligible. For not
only should the property be more intelligible than its subject, but
also it should be something whose attribution to the particular
subject is a more intelligible attribution. For he who does not know
whether it is an attribute of the particular subject at all, will
not know either whether it belongs to it alone, so that whichever of
these results happens, its character as a property becomes obscure.
Thus (e.g.) a man who has stated that it is a property of fire to be
'the primary element wherein the soul is naturally found', has
introduced a subject which is less intelligible than 'fire', viz.
whether the soul is found in it, and whether it is found there
primarily; and therefore to be 'the primary element in which the
soul is naturally found' could not be correctly stated to be a
property of 'fire'. On the other hand, for constructive purposes,
see whether the terms in which the property is stated are more
intelligible, and if they are more intelligible in each of the
aforesaid ways. For then the property will have been correctly
stated in this respect: for of constructive arguments, showing the
correctness of a rendering, some will show the correctness merely in
this respect, while others will show it without qualification. Thus
(e.g.) a man who has said that the 'possession of sensation' is a
property of 'animal' has both used more intelligible terms and has
rendered the property more intelligible in each of the aforesaid
senses; so that to 'possess sensation' would in this respect have been
correctly rendered as a property of 'animal'.
  Next, for destructive purposes, see whether any of the terms
rendered in the property is used in more than one sense, or whether
the whole expression too signifies more than one thing. For then the
property will not have been correctly stated. Thus (e.g.) seeing
that to 'being natural sentient' signifies more than one thing, viz.
(1) to possess sensation, (2) to use one's sensation, being
naturally sentient' could not be a correct statement of a property
of 'animal'. The reason why the term you use, or the whole
expression signifying the property, should not bear more than one
meaning is this, that an expression bearing more than one meaning
makes the object described obscure, because the man who is about to
attempt an argument is in doubt which of the various senses the
expression bears: and this will not do, for the object of rendering
the property is that he may understand. Moreover, in addition to this,
it is inevitable that those who render a property after this fashion
should be somehow refuted whenever any one addresses his syllogism
to that one of the term's several meanings which does not agree. For
constructive purposes, on the other hand, see whether both all the
terms and also the expression as a whole avoid bearing more than one
sense: for then the property will have been correctly stated in this
respect. Thus (e.g.) seeing that 'body' does not bear several
meanings, nor quickest to move upwards in space', nor yet the whole
expression made by putting them together, it would be correct in
this respect to say that it is a property of fire to be the 'body
quickest to move upwards in space'.
  Next, for destructive purposes, see if the term of which he
renders the property is used in more than one sense, and no
distinction has been drawn as to which of them it is whose property he
is stating: for then the property will not have been correctly
rendered. The reasons why this is so are quite clear from what has
been said above: for the same results are bound to follow. Thus (e.g.)
seeing that 'the knowledge of this' signifies many things for it means
(1) the possession of knowledge by it, (2) the use of its knowledge by
it, (3) the existence of knowledge about it, (4) the use of
knowledge about it-no property of the 'knowledge of this' could be
rendered correctly unless he draw a distinction as to which of these
it is whose property he is rendering. For constructive purposes, a man
should see if the term of which he is rendering the property avoids
bearing many senses and is one and simple: for then the property
will have been correctly stated in this respect. Thus (e.g.) seeing
that 'man' is used in a single sense, 'naturally civilized animal'
would be correctly stated as a property of man.
  Next, for destructive purposes, see whether the same term has been
repeated in the property. For people often do this undetected in
rendering 'properties' also, just as they do in their 'definitions' as
well: but a property to which this has happened will not have been
correctly stated: for the repetition of it confuses the hearer; thus
inevitably the meaning becomes obscure, and further, such people are
thought to babble. Repetition of the same term is likely to happen
in two ways; one is, when a man repeatedly uses the same word, as
would happen if any one were to render, as a property of fire, 'the
body which is the most rarefied of bodies' (for he has repeated the
word 'body'); the second is, if a man replaces words by their
definitions, as would happen if any one were to render, as a
property of earth, 'the substance which is by its nature most easily
of all bodies borne downwards in space', and were then to substitute
'substances of such and such a kind' for the word 'bodies': for 'body'
and 'a substance of such and such a kind' mean one and the same thing.
For he will have repeated the word 'substance', and accordingly
neither of the properties would be correctly stated. For
constructive purposes, on the other hand, see whether he avoids ever
repeating the same term; for then the property will in this respect
have been correctly rendered. Thus (e.g.) seeing that he who has
stated 'animal capable of acquiring knowledge' as a property of man
has avoided repeating the same term several times, the property
would in this respect have been correctly rendered of man.
  Next, for destructive purposes, see whether he has rendered in the
property any such term as is a universal attribute. For one which does
not distinguish its subject from other things is useless, and it is
the business of the language Of 'properties', as also of the
language of definitions, to distinguish. In the case contemplated,
therefore, the property will not have been correctly rendered. Thus
(e.g.) a man who has stated that it is a property of knowledge to be a
'conception incontrovertible by argument, because of its unity', has
used in the property a term of that kind, viz. 'unity', which is a
universal attribute; and therefore the property of knowledge could not
have been correctly stated. For constructive purposes, on the other
hand, see whether he has avoided all terms that are common to
everything and used a term that distinguishes the subject from
something: for then the property will in this respect have been
correctly stated. Thus (e.g.) inasmuch as he who has said that it is a
property of a 'living creature' to 'have a soul' has used no term that
is common to everything, it would in this respect have been
correctly stated to be a property of a 'living creature' to 'have a
soul'.
  Next, for destructive purposes see whether he renders more than
one property of the same thing, without a definite proviso that he
is stating more than one: for then the property will not have been
correctly stated. For just as in the case of definitions too there
should be no further addition beside the expression which shows the
essence, so too in the case of properties nothing further should be
rendered beside the expression that constitutes the property
mentioned: for such an addition is made to no purpose. Thus (e.g.) a
man who has said that it is a property of fire to be 'the most
rarefied and lightest body' has rendered more than one property (for
each term is a true predicate of fire alone); and so it could not be a
correctly stated property of fire to be 'the most rarefied and
lightest body'. On the other hand, for constructive purposes, see
whether he has avoided rendering more than one property of the same
thing, and has rendered one only: for then the property will in this
respect have been correctly stated. Thus (e.g.) a man who has said
that it is a property of a liquid to be a 'body adaptable to every
shape' has rendered as its property a single character and not
several, and so the property of 'liquid' would in this respect have
been correctly stated.

                                 3

  Next, for destructive purposes, see whether he has employed either
the actual subject whose property he is rendering, or any of its
species: for then the property will not have been correctly stated.
For the object of rendering the property is that people may
understand: now the subject itself is just as unintelligible as it was
to start with, while any one of its species is posterior to it, and so
is no more intelligible. Accordingly it is impossible to understand
anything further by the use of these terms. Thus (e.g.) any one who
has said that it is property of 'animal' to be 'the substance to which
"man" belongs as a species' has employed one of its species, and
therefore the property could not have been correctly stated. For
constructive purposes, on the other hand, see whether he avoids
introducing either the subject itself or any of its species: for
then the property will in this respect have been correctly stated.
Thus (e.g.) a man who has stated that it is a property of a living
creature to be 'compounded of soul and body' has avoided introducing
among the rest either the subject itself or any of its species, and
therefore in this respect the property of a 'living creature' would
have been correctly rendered.
  You should inquire in the same way also in the case of other terms
that do or do not make the subject more intelligible: thus, for
destructive purposes, see whether he has employed anything either
opposite to the subject or, in general, anything simultaneous by
nature with it or posterior to it: for then the property will not have
been correctly stated. For an opposite is simultaneous by nature
with its opposite, and what is simultaneous by nature or is
posterior to it does not make its subject more intelligible. Thus
(e.g.) any one who has said that it is a property of good to be 'the
most direct opposite of evil', has employed the opposite of good,
and so the property of good could not have been correctly rendered.
For constructive purposes, on the other hand, see whether he has
avoided employing anything either opposite to, or, in general,
simultaneous by nature with the subject, or posterior to it: for
then the property will in this respect have been correctly rendered.
Thus (e.g.) a man who has stated that it is a property of knowledge to
be 'the most convincing conception' has avoided employing anything
either opposite to, or simultaneous by nature with, or posterior to,
the subject; and so the property of knowledge would in this respect
have been correctly stated.
  Next, for destructive purposes, see whether he has rendered as
property something that does not always follow the subject but
sometimes ceases to be its property: for then the property will not
have been correctly described. For there is no necessity either that
the name of the subject must also be true of anything to which we find
such an attribute belonging; nor yet that the name of the subject will
be untrue of anything to which such an attribute is found not to
belong. Moreover, in addition to this, even after he has rendered
the property it will not be clear whether it belongs, seeing that it
is the kind of attribute that may fall: and so the property will not
be clear. Thus (e.g.) a man who has stated that it is a property of
animal 'sometimes to move and sometimes to stand still' rendered the
kind of property which sometimes is not a property, and so the
property could not have been correctly stated. For constructive
purposes, on the other hand, see whether he has rendered something
that of necessity must always be a property: for then the property
will have been in this respect correctly stated. Thus (e.g.) a man who
has stated that it is a property of virtue to be 'what makes its
possessor good' has rendered as property something that always
follows, and so the property of virtue would in this respect have been
correctly rendered.
  Next, for destructive purposes, see whether in rendering the
property of the present time he has omitted to make a definite proviso
that it is the property of the present time which he is rendering: for
else the property will not have been correctly stated. For in the
first place, any unusual procedure always needs a definite proviso:
and it is the usual procedure for everybody to render as property some
attribute that always follows. In the second place, a man who omits to
provide definitely whether it was the property of the present time
which he intended to state, is obscure: and one should not give any
occasion for adverse criticism. Thus (e.g.) a man who has stated it as
the property of a particular man 'to be sitting with a particular
man', states the property of the present time, and so he cannot have
rendered the property correctly, seeing that he has described it
without any definite proviso. For constructive purposes, on the
other hand, see whether, in rendering the property of the present
time, he has, in stating it, made a definite proviso that it is the
property of the present time that he is stating: for then the property
will in this respect have been correctly stated. Thus (e.g.) a man who
has said that it is the property of a particular man 'to be walking
now', has made this distinction in his statement, and so the
property would have been correctly stated.
  Next, for destructive purposes, see whether he has rendered a
property of the kind whose appropriateness is not obvious except by
sensation: for then the property will not have been correctly
stated. For every sensible attribute, once it is taken beyond the
sphere of sensation, becomes uncertain. For it is not clear whether it
still belongs, because it is evidenced only by sensation. This
principle will be true in the case of any attributes that do not
always and necessarily follow. Thus (e.g.) any one who has stated that
it is a property of the sun to be 'the brightest star that moves
over the earth', has used in describing the property an expression
of that kind, viz. 'to move over the earth', which is evidenced by
sensation; and so the sun's property could not have been correctly
rendered: for it will be uncertain, whenever the sun sets, whether
it continues to move over the earth, because sensation then fails
us. For constructive purposes, on the other hand, see whether he has
rendered the property of a kind that is not obvious to sensation,
or, if it be sensible, must clearly belong of necessity: for then
the property will in this respect have been correctly stated. Thus
(e.g.) a man who has stated that it is a property of a surface to be
'the primary thing that is coloured', has introduced amongst the
rest a sensible quality, 'to be coloured', but still a quality such as
manifestly always belongs, and so the property of 'surface' would in
this respect have been correctly rendered.
  Next, for destructive purposes, see whether he has rendered the
definition as a property: for then the property will not have been
correctly stated: for the property of a thing ought not to show its
essence. Thus (e.g.) a man who has said that it is the property of man
to be 'a walking, biped animal' has rendered a property of man so as
to signify his essence, and so the property of man could not have been
correctly rendered. For constructive purposes, on the other hand,
see whether the property which he has rendered forms a predicate
convertible with its subject, without, however, signifying its
essence: for then the property will in this respect have been
correctly rendered. Thus (e.g.) he who has stated that it is a
property of man to be a 'naturally civilized animal' has rendered
the property so as to be convertible with its subject, without,
however, showing its essence, and so the property of man' would in
this respect have been correctly rendered.
  Next, for destructive purposes, see whether he has rendered the
property without having placed the subject within its essence. For
of properties, as also of definitions, the first term to be rendered
should be the genus, and then the rest of it should be appended
immediately afterwards, and should distinguish its subject from
other things. Hence a property which is not stated in this way could
not have been correctly rendered. Thus (e.g.) a man who has said
that it is a property of a living creature to 'have a soul' has not
placed 'living creature' within its essence, and so the property of
a living creature could not have been correctly stated. For
constructive purposes, on the other hand, see whether a man first
places within its essence the subject whose property he is
rendering, and then appends the rest: for then the property will in
this respect have been correctly rendered. Thus (e.g.) he who has
stated that is a property of man to be an 'animal capable of receiving
knowledge', has rendered the property after placing the subject within
its essence, and so the property of 'man' would in this respect have
been correctly rendered.

                                 4

  The inquiry, then, whether the property has been correctly
rendered or no, should be made by these means. The question, on the
other hand, whether what is stated is or is not a property at all, you
should examine from the following points of view. For the
commonplace arguments which establish absolutely that the property
is accurately stated will be the same as those that constitute it a
property at all: accordingly they will be described in the course of
them.
  Firstly, then, for destructive purposes, take a look at each subject
of which he has rendered the property, and see (e.g.) if it fails to
belong to any of them at all, or to be true of them in that particular
respect, or to be a property of each of them in respect of that
character of which he has rendered the property: for then what is
stated to be a property will not be a property. Thus, for example,
inasmuch as it is not true of the geometrician that he 'cannot be
deceived by an argument' (for a geometrician is deceived when his
figure is misdrawn), it could not be a property of the man of
science that he is not deceived by an argument. For constructive
purposes, on the other hand, see whether the property rendered be true
of every instance, and true in that particular respect: for then
what is stated not to be a property will be a property. Thus, for
example, in as much as the description 'an animal capable of receiving
knowledge' is true of every man, and true of him qua man, it would
be a property of man to be 'an animal capable of receiving knowledge'.
commonplace rule means-for destructive purposes, see if the
description fails to be true of that of which the name is true; and if
the name fails to be true of that of which the description is true:
for constructive purposes, on the other hand, see if the description
too is predicated of that of which the name is predicated, and if
the name too is predicated of that of which the description is
predicated.]
  Next, for destructive purposes, see if the description fails to
apply to that to which the name applies, and if the name fails to
apply to that to which the description applies: for then what is
stated to be a property will not be a property. Thus (e.g.) inasmuch
as the description 'a living being that partakes of knowledge' is true
of God, while 'man' is not predicated of God, to be a living being
that partakes of knowledge' could not be a property of man. For
constructive purposes, on the other hand, see if the name as well be
predicated of that of which the description is predicated, and if
the description as well be predicated of that of which the name is
predicated. For then what is stated not to be a property will be a
property. Thus (e.g.) the predicate 'living creature' is true of
that of which 'having a soul' is true, and 'having a soul' is true
of that of which the predicate 'living creature' is true; and so
'having a soul would be a property of 'living creature'.
  Next, for destructive purposes, see if he has rendered a subject
as a property of that which is described as 'in the subject': for then
what has been stated to be a property will not be a property. Thus
(e.g.) inasmuch as he who has rendered 'fire' as the property of
'the body with the most rarefied particles', has rendered the
subject as the property of its predicate, 'fire' could not be a
property of 'the body with the most rarefied particles'. The reason
why the subject will not be a property of that which is found in the
subject is this, that then the same thing will be the property of a
number of things that are specifically different. For the same thing
has quite a number of specifically different predicates that belong to
it alone, and the subject will be a property of all of these, if any
one states the property in this way. For constructive purposes, on the
other hand, see if he has rendered what is found in the subject as a
property of the subject: for then what has been stated not to be a
property will be a property, if it be predicated only of the things of
which it has been stated to be the property. Thus (e.g.) he who has
said that it is a property of 'earth' to be 'specifically the heaviest
body' has rendered of the subject as its property something that is
said of the thing in question alone, and is said of it in the manner
in which a property is predicated, and so the property of earth
would have been rightly stated.
  Next, for destructive purposes, see if he has rendered the
property as partaken of: for then what is stated to be a property will
not be a property. For an attribute of which the subject partakes is a
constituent part of its essence: and an attribute of that kind would
be a differentia applying to some one species. E.g. inasmuch as he who
has said that 'walking on two feet' is property of man has rendered
the property as partaken of, 'walking on two feet' could not be a
property of 'man'. For constructive purposes, on the other hand, see
if he has avoided rendering the property as partaken of, or as showing
the essence, though the subject is predicated convertibly with it: for
then what is stated not to be a property will be a property. Thus
(e.g.) he who has stated that to be 'naturally sentient' is a property
of 'animal' has rendered the property neither as partaken of nor as
showing the essence, though the subject is predicated convertibly with
it; and so to be 'naturally sentient' would be a property of 'animal'.
  Next, for destructive purposes, see if the property cannot
possibly belong simultaneously, but must belong either as posterior or
as prior to the attribute described in the name: for then what is
stated to be a property will not be a property either never, or not
always. Thus (e.g.) inasmuch as it is possible for the attribute
'walking through the market-place' to belong to an object as prior and
as posterior to the attribute 'man', 'walking through the
market-place' could not be a property of 'man' either never, or not
always. For constructive purposes, on the other hand, see if it always
and of necessity belongs simultaneously, without being either a
definition or a differentia: for then what is stated not to be a
property will be a property. Thus (e.g.) the attribute 'an animal
capable of receiving knowledge' always and of necessity belongs
simultaneously with the attribute 'man', and is neither differentia
nor definition of its subject, and so 'an animal capable of
receiving knowledge' would be a property of 'man'.
  Next, for destructive purposes, see if the same thing fails to be
a property of things that are the same as the subject, so far as
they are the same: for then what is stated to be a property will not
be a property. Thus, for example, inasmuch as it is no property of a
'proper object of pursuit' to 'appear good to certain persons', it
could not be a property of the 'desirable' either to 'appear good to
certain persons': for 'proper object of pursuit' and 'desirable'
mean the same. For constructive purposes, on the other hand, see if
the same thing be a property of something that is the same as the
subject, in so far as it is the same. For then is stated not to be a
property will be a property. Thus (e.g.) inasmuch as it is called a
property of a man, in so far as he is a man, 'to have a tripartite
soul', it would also be a property of a mortal, in so far as he is a
mortal, to have a tripartite soul. This commonplace rule is useful
also in dealing with Accident: for the same attributes ought either to
belong or not belong to the same things, in so far as they are the
same.
  Next, for destructive purposes, see if the property of things that
are the same in kind as the subject fails to be always the same in
kind as the alleged property: for then neither will what is stated
to be the property of the subject in question. Thus (e.g.) inasmuch as
a man and a horse are the same in kind, and it is not always a
property of a horse to stand by its own initiative, it could not be
a property of a man to move by his own initiative; for to stand and to
move by his own initiative are the same in kind, because they belong
to each of them in so far as each is an 'animal'. For constructive
purposes, on the other hand, see if of things that are the same in
kind as the subject the property that is the same as the alleged
property is always true: for then what is stated not to be a
property will be a property. Thus (e.g.) since it is a property of man
to be a 'walking biped,' it would also be a property of a bird to be a
'flying biped': for each of these is the same in kind, in so far as
the one pair have the sameness of species that fall under the same
genus, being under the genus 'animal', while the other pair have
that of differentiae of the genus, viz. of 'animal'. This
commonplace rule is deceptive whenever one of the properties mentioned
belongs to some one species only while the other belongs to many, as
does 'walking quadruped'.
  Inasmuch as 'same' and 'different' are terms used in several senses,
it is a job to render to a sophistical questioner a property that
belongs to one thing and that only. For an attribute that belongs to
something qualified by an accident will also belong to the accident
taken along with the subject which it qualifies; e.g. an attribute
that belongs to 'man' will belong also to 'white man', if there be a
white man, and one that belongs to 'white man' will belong also to
'man'. One might, then, bring captious criticism against the
majority of properties, by representing the subject as being one thing
in itself, and another thing when combined with its accident,
saying, for example, that 'man' is one thing, and white man'
another, and moreover by representing as different a certain state and
what is called after that state. For an attribute that belongs to
the state will belong also to what is called after that state, and one
that belongs to what is called after a state will belong also to the
state: e.g. inasmuch as the condition of the scientist is called after
his science, it could not be a property of 'science' that it is
'incontrovertible by argument'; for then the scientist also will be
incontrovertible by argument. For constructive purposes, however,
you should say that the subject of an accident is not absolutely
different from the accident taken along with its subject; though it is
called 'another' thing because the mode of being of the two is
different: for it is not the same thing for a man to be a man and
for a white man to be a white man. Moreover, you should take a look
along at the inflections, and say that the description of the man of
science is wrong: one should say not 'it' but 'he is
incontrovertible by argument'; while the description of Science is
wrong too: one should say not 'it' but 'she is incontrovertible by
argument'. For against an objector who sticks at nothing the defence
should stick at nothing.

                                 5

  Next, for destructive purposes, see if, while intending to render an
attribute that naturally belongs, he states it in his language in such
a way as to indicate one that invariably belongs: for then it would be
generally agreed that what has been stated to be a property is
upset. Thus (e.g.) the man who has said that 'biped' is a property
of man intends to render the attribute that naturally belongs, but his
expression actually indicates one that invariably belongs:
accordingly, 'biped' could not be a property of man: for not every man
is possessed of two feet. For constructive purposes, on the other
hand, see if he intends to render the property that naturally belongs,
and indicates it in that way in his language: for then the property
will not be upset in this respect. Thus (e.g.) he who renders as a
property of 'man' the phrase 'an animal capable of receiving
knowledge' both intends, and by his language indicates, the property
that belongs by nature, and so 'an animal capable of receiving
knowledge' would not be upset or shown in that respect not to be a
property of man.
  Moreover, as regards all the things that are called as they are
primarily after something else, or primarily in themselves, it is a
job to render the property of such things. For if you render a
property as belonging to the subject that is so called after something
else, then it will be true of its primary subject as well; whereas
if you state it of its primary subject, then it will be predicated
also of the thing that is so called after this other. Thus (e.g.) if
any one renders , coloured' as the property of 'surface', 'coloured'
will be true of body as well; whereas if he render it of 'body', it
will be predicated also of 'surface'. Hence the name as well will
not be true of that of which the description is true.
  In the case of some properties it mostly happens that some error
is incurred because of a failure to define how as well as to what
things the property is stated to belong. For every one tries to render
as the property of a thing something that belongs to it either
naturally, as 'biped' belongs to 'man', or actually, as 'having four
fingers' belongs to a particular man, or specifically, as
'consisting of most rarefied particles' belongs to 'fire', or
absolutely, as 'life' to 'living being', or one that belongs to a
thing only as called after something else, as 'wisdom' to the
'soul', or on the other hand primarily, as 'wisdom' to the 'rational
faculty', or because the thing is in a certain state, as
'incontrovertible by argument' belongs to a 'scientist' (for simply
and solely by reason of his being in a certain state will he be
'incontrovertible by argument'), or because it is the state
possessed by something, as 'incontrovertible by argument' belongs to
'science', or because it is partaken of, as 'sensation' belongs to
'animal' (for other things as well have sensation, e.g. man, but
they have it because they already partake of 'animal'), or because
it partakes of something else, as 'life' belongs to a particular
kind of 'living being'. Accordingly he makes a mistake if he has
failed to add the word 'naturally', because what belongs naturally may
fail to belong to the thing to which it naturally belongs, as (e.g.)
it belongs to a man to have two feet: so too he errs if he does not
make a definite proviso that he is rendering what actually belongs,
because one day that attribute will not be what it now is, e.g. the
man's possession of four fingers. So he errs if he has not shown
that he states a thing to be such and such primarily, or that he calls
it so after something else, because then its name too will not be true
of that of which the description is true, as is the case with
'coloured', whether rendered as a property of 'surface' or of
'body'. So he errs if he has not said beforehand that he has
rendered a property to a thing either because that thing possesses a
state, or because it is a state possessed by something; because then
it will not be a property. For, supposing he renders the property to
something as being a state possessed, it will belong to what possesses
that state; while supposing he renders it to what possesses the state,
it will belong to the state possessed, as did 'incontrovertible by
argument' when stated as a property of 'science' or of the
'scientist'. So he errs if he has not indicated beforehand that the
property belongs because the thing partakes of, or is partaken of
by, something; because then the property will belong to certain
other things as well. For if he renders it because its subject is
partaken of, it will belong to the things which partake of it; whereas
if he renders it because its subject partakes of something else, it
will belong to the things partaken of, as (e.g.) if he were to state
'life' to be a property of a 'particular kind of living being', or
just of 'living being. So he errs if he has not expressly
distinguished the property that belongs specifically, because then
it will belong only to one of the things that fall under the term of
which he states the property: for the superlative belongs only to
one of them, e.g. 'lightest' as applied to 'fire'. Sometimes, too, a
man may even add the word 'specifically', and still make a mistake.
For the things in question should all be of one species, whenever
the word 'specifically' is added: and in some cases this does not
occur, as it does not, in fact, in the case of fire. For fire is not
all of one species; for live coals and flame and light are each of
them 'fire', but are of different species. The reason why, whenever
'specifically' is added, there should not be any species other than
the one mentioned, is this, that if there be, then the property in
question will belong to some of them in a greater and to others in a
less degree, as happens with 'consisting of most rarefied particles'
in the case of fire: for 'light' consists of more rarefied particles
than live coals and flame. And this should not happen unless the
name too be predicated in a greater degree of that of which the
description is truer; otherwise the rule that where the description is
truer the name too should be truer is not fulfilled. Moreover, in
addition to this, the same attribute will be the property both of
the term which has it absolutely and of that element therein which has
it in the highest degree, as is the condition of the property
'consisting of most rarefied particles' in the case of 'fire': for
this same attribute will be the property of 'light' as well: for it is
'light' that 'consists of the most rarefied particles'. If, then,
any one else renders a property in this way one should attack it;
for oneself, one should not give occasion for this objection, but
should define in what manner one states the property at the actual
time of making the statement.
  Next, for destructive purposes, see if he has stated a thing as a
property of itself: for then what has been stated to be a property
will not be a property. For a thing itself always shows its own
essence, and what shows the essence is not a property but a
definition. Thus (e.g.) he who has said that 'becoming' is a
property of 'beautiful' has rendered the term as a property of
itself (for 'beautiful' and 'becoming' are the same); and so
'becoming' could not be a property of 'beautiful'. For constructive
purposes, on the other hand, see if he has avoided rendering a thing
as a property of itself, but has yet stated a convertible predicate:
for then what is stated not to be a property will be a property.
Thus he who has stated 'animate substance' as a property of
'living-creature' has not stated 'living-creature' as a property of
itself, but has rendered a convertible predicate, so that 'animate
substance' would be a property of 'living-creature'.
  Next, in the case of things consisting of like parts, you should
look and see, for destructive purposes, if the property of the whole
be not true of the part, or if that of the part be not predicated of
the whole: for then what has been stated to be the property will not
be a property. In some cases it happens that this is so: for sometimes
in rendering a property in the case of things that consist of like
parts a man may have his eye on the whole, while sometimes he may
address himself to what is predicated of the part: and then in neither
case will it have been rightly rendered. Take an instance referring to
the whole: the man who has said that it is a property of the 'sea'
to be 'the largest volume of salt water', has stated the property of
something that consists of like parts, but has rendered an attribute
of such a kind as is not true of the part (for a particular sea is not
'the largest volume of salt water'); and so the largest volume of salt
water' could not be a property of the 'sea'. Now take one referring to
the part: the man who has stated that it is a property of 'air' to
be 'breathable' has stated the property of something that consists
of like parts, but he has stated an attribute such as, though true
of some air, is still not predicable of the whole (for the whole of
the air is not breathable); and so 'breathable' could not be a
property of 'air'. For constructive purposes, on the other hand, see
whether, while it is true of each of the things with similar parts, it
is on the other hand a property of them taken as a collective whole:
for then what has been stated not to be a property will be a property.
Thus (e.g.) while it is true of earth everywhere that it naturally
falls downwards, it is a property of the various particular pieces
of earth taken as 'the Earth', so that it would be a property of
'earth' 'naturally to fall downwards'.

                                 6

  Next, look from the point of view of the respective opposites, and
first (a) from that of the contraries, and see, for destructive
purposes, if the contrary of the term rendered fails to be a
property of the contrary subject. For then neither will the contrary
of the first be a property of the contrary of the second. Thus
(e.g.) inasmuch as injustice is contrary to justice, and the lowest
evil to the highest good, but 'to be the highest good' is not a
property of 'justice', therefore 'to be the lowest evil' could not
be a property of 'injustice'. For constructive purposes, on the
other hand, see if the contrary is the property of the contrary: for
then also the contrary of the first will be the property of the
contrary of the second. Thus (e.g.) inasmuch as evil is contrary to
good, and objectionable to desirable, and 'desirable' is a property of
'good', 'objectionable' would be a property of 'evil'.
  Secondly (h) look from the point of view of relative opposites and
see, for destructive purposes, if the correlative of the term rendered
fails to be a property of the correlative of the subject: for then
neither will the correlative of the first be a property of the
correlative of the second. Thus (e.g.) inasmuch as 'double' is
relative to 'half', and 'in excess' to 'exceeded', while 'in excess'
is not a property of 'double', exceeded' could not be a property of
'half'. For constructive purposes, on the other hand, see if the
correlative of the alleged property is a property of the subject's
correlative: for then also the correlative of the first will be a
property of the correlative of the second: e.g. inasmuch as 'double'
is relative to 'half', and the proportion 1:2 is relative to the
proportion 2:1, while it is a property of 'double' to be 'in the
proportion of 2 to 1', it would be a property of 'half' to be 'in
the proportion of 1 to 2'.
  Thirdly (c) for destructive purposes, see if an attribute
described in terms of a state (X) fails to be a property of the
given state (Y): for then neither will the attribute described in
terms of the privation (of X) be a property of the privation (of Y).
Also if, on the other hand, an attribute described in terms of the
privation (of X) be not a property of the given privation (of Y),
neither will the attribute described in terms of the state (X) be a
property of the state (Y). Thus, for example, inasmuch as it is not
predicated as a property of 'deafness' to be a 'lack of sensation',
neither could it be a property of 'hearing' to be a 'sensation'. For
constructive purposes, on the other hand, see if an attribute
described in terms of a state (X) is a property of the given state
(Y): for then also the attribute that is described in terms of the
privation (of X) will be a property of the privation (of Y). Also,
if an attribute described in terms of a privation (of X) be a property
of the privation (of Y), then also the attribute that is described
in terms of the state (X) will be a property of the state (Y). Thus
(e.g.) inasmuch as 'to see' is a property of 'sight', inasmuch as we
have sight, 'failure to see' would be a property of 'blindness',
inasmuch as we have not got the sight we should naturally have.
  Next, look from the point of view of positive and negative terms;
and first (a) from the point of view of the predicates taken by
themselves. This common-place rule is useful only for a destructive
purpose. Thus (e.g.) see if the positive term or the attribute
described in terms of it is a property of the subject: for then the
negative term or the attribute described in terms of it will not be
a property of the subject. Also if, on the other hand, the negative
term or the attribute described in terms of it is a property of the
subject, then the positive term or the attribute described in terms of
it will not be a property of the subject: e.g. inasmuch as 'animate'
is a property of 'living creature', 'inanimate' could not be a
property of 'living creature'.
  Secondly (b) look from the point of view of the predicates, positive
or negative, and their respective subjects; and see, for destructive
purposes, if the positive term falls to be a property of the
positive subject: for then neither will the negative term be a
property of the negative subject. Also, if the negative term fails
to be a property of the negative subject, neither will the positive
term be a property of the positive subject. Thus (e.g.) inasmuch as
'animal' is not a property of 'man', neither could 'not-animal' be a
property of 'not-man'. Also if 'not-animal' seems not to be a property
of 'not-man', neither will 'animal' be a property of 'man'. For
constructive purposes, on the other hand, see if the positive term
is a property of the positive subject: for then the negative term will
be a property of the negative subject as well. Also if the negative
term be a property of the negative subject, the positive will be a
property of the positive as well. Thus (e.g.) inasmuch as it is a
property of 'not-living being' 'not to live', it would be a property
of 'living being' 'to live': also if it seems to be a property of
'living being' 'to live', it will also seem to be a property of
'not-living being' 'not to live'.
  Thirdly (c) look from the point of view of the subjects taken by
themselves, and see, for destructive purposes, if the property
rendered is a property of the positive subject: for then the same term
will not be a property of the negative subject as well. Also, if the
term rendered be a property of the negative subject, it will not be
a property of the positive. Thus (e.g.) inasmuch as 'animate' is a
property of 'living creature', 'animate' could not be a property of
'not-living creature'. For constructive purposes, on the other hand,
if the term rendered fails to be a property of the affirmative subject
it would be a property of the negative. This commonplace rule is,
however, deceptive: for a positive term is not a property of a
negative, or a negative of a positive. For a positive term does not
belong at all to a negative, while a negative term, though it
belongs to a positive, does not belong as a property.
  Next, look from the point of view of the coordinate members of a
division, and see, for destructive purposes, if none of the
co-ordinate members (parallel with the property rendered) be a
property of any of the remaining set of co-ordinate members
(parallel with the subject): for then neither will the term stated
be a property of that of which it is stated to be a property. Thus
(e.g.) inasmuch as 'sensible living being' is not a property of any of
the other living beings, 'intelligible living being' could not be a
property of God. For constructive purposes, on the other hand, see
if some one or other of the remaining co-ordinate members (parallel
with the property rendered) be a property of each of these co-ordinate
members (parallel with the subject): for then the remaining one too
will be a property of that of which it has been stated not to be a
property. Thus (e.g.) inasmuch as it is a property of 'wisdom' to be
essentially 'the natural virtue of the rational faculty', then, taking
each of the other virtues as well in this way, it would be a
property of 'temperance' to be essentially 'the natural virtue of
the faculty of desire'.
  Next, look from the point of view of the inflexions, and see, for
destructive purposes, if the inflexion of the property rendered
fails to be a property of the inflexion of the subject: for then
neither will the other inflexion be a property of the other inflexion.
Thus (e.g.) inasmuch as 'beautifully' is not a property of 'justly',
neither could 'beautiful' be a property of 'just'. For constructive
purposes, on the other hand, see if the inflexion of the property
rendered is a property of the inflexion of the subject: for then
also the other inflexion will be a property of the other inflexion.
Thus (e.g.) inasmuch as 'walking biped' is a property of man, it would
also be any one's property 'as a man' to be described 'as a walking
biped'. Not only in the case of the actual term mentioned should one
look at the inflexions, but also in the case of its opposites, just as
has been laid down in the case of the former commonplace rules as
well.' Thus, for destructive purposes, see if the inflexion of the
opposite of the property rendered fails to be the property of the
inflexion of the opposite of the subject: for then neither will the
inflexion of the other opposite be a property of the inflexion of
the other opposite. Thus (e.g.) inasmuch as 'well' is not a property
of 'justly', neither could 'badly' be a property of 'unjustly'. For
constructive purposes, on the other hand, see if the inflexion of
the opposite of the property originally suggested is a property of the
inflexion of the opposite of the original subject: for then also the
inflexion of the other opposite will be a property of the inflexion of
the other opposite. Thus (e.g.) inasmuch as 'best' is a property of
'the good', 'worst' also will be a property of 'the evil'.

                                 7

  Next, look from the point of view of things that are in a like
relation, and see, for destructive purposes, if what is in a
relation like that of the property rendered fails to be a property
of what is in a relation like that of the subject: for then neither
will what is in a relation like that of the first be a property of
what is in a relation like that of the second. Thus (e.g.) inasmuch as
the relation of the builder towards the production of a house is
like that of the doctor towards the production of health, and it is
not a property of a doctor to produce health, it could not be a
property of a builder to produce a house. For constructive purposes,
on the other hand, see if what is in a relation like that of the
property rendered is a property of what is in a relation like that
of the subject: for then also what is in a relation like that of the
first will be a property of what is in a relation like that of the
second. Thus (e.g.) inasmuch as the relation of a doctor towards the
possession of ability to produce health is like that of a trainer
towards the possession of ability to produce vigour, and it is a
property of a trainer to possess the ability to produce vigour, it
would be a property of a doctor to possess the ability to produce
health.
  Next look from the point of view of things that are identically
related, and see, for destructive purposes, if the predicate that is
identically related towards two subjects fails to be a property of the
subject which is identically related to it as the subject in question;
for then neither will the predicate that is identically related to
both subjects be a property of the subject which is identically
related to it as the first. If, on the other hand, the predicate which
is identically related to two subjects is the property of the
subject which is identically related to it as the subject in question,
then it will not be a property of that of which it has been stated
to be a property. (e.g.) inasmuch as prudence is identically related
to both the noble and the base, since it is knowledge of each of them,
and it is not a property of prudence to be knowledge of the noble,
it could not be a property of prudence to be knowledge of the base.
If, on the other hand, it is a property of prudence to be the
knowledge of the noble, it could not be a property of it to be the
knowledge of the base.] For it is impossible for the same thing to
be a property of more than one subject. For constructive purposes,
on the other hand, this commonplace rule is of no use: for what is
'identically related' is a single predicate in process of comparison
with more than one subject.
  Next, for destructive purposes, see if the predicate qualified by
the verb 'to be' fails to be a property of the subject qualified by
the verb 'to be': for then neither will the destruction of the one
be a property of the other qualified by the verb 'to be destroyed',
nor will the 'becoming'the one be a property of the other qualified by
the verb 'to become'. Thus (e.g.) inasmuch as it is not a property
of 'man' to be an animal, neither could it be a property of becoming a
man to become an animal; nor could the destruction of an animal be a
property of the destruction of a man. In the same way one should
derive arguments also from 'becoming' to 'being' and 'being
destroyed', and from 'being destroyed' to 'being' and to 'becoming'
exactly as they have just been given from 'being' to 'becoming' and
'being destroyed'. For constructive purposes, on the other hand, see
if the subject set down as qualified by the verb 'to be' has the
predicate set down as so qualified, as its property: for then also the
subject qualified by the very 'to become' will have the predicate
qualified by 'to become' as its property, and the subject qualified by
the verb to be destroyed' will have as its property the predicate
rendered with this qualification. Thus, for example, inasmuch as it is
a property of man to be a mortal, it would be a property of becoming a
man to become a mortal, and the destruction of a mortal would be a
property of the destruction of a man. In the same way one should
derive arguments also from 'becoming' and 'being destroyed' both to
'being' and to the conclusions that follow from them, exactly as was
directed also for the purpose of destruction.
  Next take a look at the 'idea' of the subject stated, and see, for
destructive purposes, if the suggested property fails to belong to the
'idea' in question, or fails to belong to it in virtue of that
character which causes it to bear the description of which the
property was rendered: for then what has been stated to be a
property will not be a property. Thus (e.g.) inasmuch as 'being
motionless' does not belong to 'man-himself' qua 'man', but qua
'idea', it could not be a property of 'man' to be motionless. For
constructive purposes, on the other hand, see if the property in
question belongs to the idea, and belongs to it in that respect in
virtue of which there is predicated of it that character of which
the predicate in question has been stated not to be a property: for
then what has been stated not to be a property will be a property.
Thus (e.g.) inasmuch as it belongs to 'living-creature-itself' to be
compounded of soul and body, and further this belongs to it qua
'living-creature', it would be a property of 'living-creature' to be
compounded of soul and body.

                                 8

  Next look from the point of view of greater and less degrees, and
first (a) for destructive purposes, see if what is more-P fails to
be a property of what is more-S: for then neither will what is
less-P be a property of what is less-S, nor least-P of least-S, nor
most-P of most-S, nor P simply of S simply. Thus (e.g.) inasmuch as
being more highly coloured is not a property of what is more a body,
neither could being less highly coloured be a property of what is less
a body, nor being coloured be a property of body at all. For
constructive purposes, on the other hand, see if what is more-P is a
property of what is more-S: for then also what is less-P will be a
property of what is less S, and least-P of least-S, and most-P of
most-S, and P simply of S simply. Thus (e.g.) inasmuch as a higher
degree of sensation is a property of a higher degree of life, a
lower degree of sensation also would be a property of a lower degree
of life, and the highest of the highest and the lowest of the lowest
degree, and sensation simply of life simply.
  Also you should look at the argument from a simple predication to
the same qualified types of predication, and see, for destructive
purposes, if P simply fails to be a property of S simply; for then
neither will more-P be a property of more-S, nor less-P of less-S, nor
most-P of most-S, nor least-P of least-S. Thus (e.g.) inasmuch as
'virtuous' is not a property of 'man', neither could 'more virtuous'
be a property of what is 'more human'. For constructive purposes, on
the other hand, see if P simply is a property of S simply: for then
more P also will be a property of more-S, and less-P of less-S, and
least-P of least-S, and most-P of most-S. Thus (e.g.) a tendency to
move upwards by nature is a property of fire, and so also a greater
tendency to move upwards by nature would be a property of what is more
fiery. In the same way too one should look at all these matters from
the point of view of the others as well.
  Secondly (b) for destructive purposes, see if the more likely
property fails to be a property of the more likely subject: for then
neither will the less likely property be a property of the less likely
subject. Thus (e.g.) inasmuch as 'perceiving' is more likely to be a
property of 'animal' than 'knowing' of 'man', and 'perceiving' is
not a property of 'animal', 'knowing' could not be a property of
'man'. For constructive purposes, on the other hand, see if the less
likely property is a property of the less likely subject; for then too
the more likely property will be a property of the more likely
subject. Thus (e.g.) inasmuch as 'to be naturally civilized' is less
likely to be a property of man than 'to live' of an animal, and it
is a property of man to be naturally civilized, it would be a property
of animal to live.
  Thirdly (c) for destructive purposes, see if the predicate fails
to be a property of that of which it is more likely to be a
property: for then neither will it be a property of that of which it
is less likely to be a property: while if it is a property of the
former, it will not be a property of the latter. Thus (e.g.)
inasmuch as 'to be coloured' is more likely to be a property of a
'surface' than of a 'body', and it is not a property of a surface, 'to
be coloured' could not be a property of 'body'; while if it is a
property of a 'surface', it could not be a property of a 'body'. For
constructive purposes, on the other hand, this commonplace rule is not
of any use: for it is impossible for the same thing to be a property
of more than one thing.
  Fourthly (d) for destructive purposes, see if what is more likely to
be a property of a given subject fails to be its property: for then
neither will what is less likely to be a property of it be its
property. Thus (e.g.) inasmuch as 'sensible' is more likely than
'divisible' to be a property of 'animal', and 'sensible' is not a
property of animal, 'divisible' could not be a property of animal. For
constructive purposes, on the other hand, see if what is less likely
to be a property of it is a property; for then what is more likely
to be a property of it will be a property as well. Thus, for
example, inasmuch as 'sensation' is less likely to be a property of
'animal' than life', and 'sensation' is a property of animal, 'life'
would be a property of animal.
  Next, look from the point of view of the attributes that belong in a
like manner, and first (a) for destructive purposes, see if what is as
much a property fails to be a property of that of which it is as
much a property: for then neither will that which is as much a
property as it be a property of that of which it is as much a
property. Thus (e.g.) inasmuch as 'desiring' is as much a property
of the faculty of desire as reasoning' is a property of the faculty of
reason, and desiring is not a property of the faculty of desire,
reasoning could not be a property of the faculty of reason. For
constructive purposes, on the other hand, see if what is as much a
property is a property of that of which it is as much a property:
for then also what is as much a property as it will be a property of
that of which it is as much a property. Thus (e.g.) inasmuch as it
is as much a property of 'the faculty of reason' to be 'the primary
seat of wisdom' as it is of 'the faculty of desire' to be 'the primary
seat of temperance', and it is a property of the faculty of reason
to be the primary seat of wisdom, it would be a property of the
faculty of desire to be the primary seat of temperance.
  Secondly (b) for destructive purposes, see if what is as much a
property of anything fails to be a property of it: for then neither
will what is as much a property be a property of it. Thus (e.g.)
inasmuch as 'seeing' is as much a property of man as 'hearing', and
'seeing' is not a property of man, 'hearing' could not be a property
of man. For constructive purposes, on the other hand, see if what is
as much a property of it is its property: for then what is as much a
property of it as the former will be its property as well. Thus (e.g.)
it is as much a property of the soul to be the primary possessor of
a part that desires as of a part that reasons, and it is a property of
the soul to be the primary possessor of a part that desires, and so it
be a property of the soul to be the primary possessor of a part that
reasons.
  Thirdly (c) for destructive purposes, see if it fails to be a
property of that of which it is as much a property: for then neither
will it be a property of that of which it is as much a property as
of the former, while if it be a property of the former, it will not be
a property of the other. Thus (e.g.) inasmuch as 'to burn' is as
much a property of 'flame' as of 'live coals', and 'to burn' is not
a property of flame, 'to burn' could not be a property of live
coals: while if it is a property of flame, it could not be a
property of live coals. For constructive purposes, on the other
hand, this commonplace rule is of no use.
  The rule based on things that are in a like relation' differs from
the rule based on attributes that belong in a like manner,' because
the former point is secured by analogy, not from reflection on the
belonging of any attribute, while the latter is judged by a comparison
based on the fact that an attribute belongs.
  Next, for destructive purposes, see if in rendering the property
potentially, he has also through that potentiality rendered the
property relatively to something that does not exist, when the
potentiality in question cannot belong to what does not exist: for
then what is stated to be a property will not be a property. Thus
(e.g.) he who has said that 'breathable' is a property of 'air' has,
on the one hand, rendered the property potentially (for that is
'breathable' which is such as can be breathed), and on the other
hand has also rendered the property relatively to what does not
exist:-for while air may exist, even though there exist no animal so
constituted as to breathe the air, it is not possible to breathe it if
no animal exist: so that it will not, either, be a property of air
to be such as can be breathed at a time when there exists no animal
such as to breathe it and so it follows that 'breathable' could not be
a property of air.
  For constructive purposes, see if in rendering the property
potentially he renders the property either relatively to something
that exists, or to something that does not exist, when the
potentiality in question can belong to what does not exist: for then
what has been stated not to be a property will be a property. Thus
e.g.) he who renders it as a property of 'being' to be 'capable of
being acted upon or of acting', in rendering the property potentially,
has rendered the property relatively to something that exists: for
when 'being' exists, it will also be capable of being acted upon or of
acting in a certain way: so that to be 'capable of being acted upon or
of acting' would be a property of 'being'.
  Next, for destructive purposes, see if he has stated the property in
the superlative: for then what has been stated to be a property will
not be a property. For people who render the property in that way find
that of the object of which the description is true, the name is not
true as well: for though the object perish the description will
continue in being none the less; for it belongs most nearly to
something that is in being. An example would be supposing any one were
to render 'the lightest body' as a property of 'fire': for, though
fire perish, there eh re will still be some form of body that is the
lightest, so that 'the lightest body' could not be a property of fire.
For constructive purposes, on the other hand, see if he has avoided
rendering the property in the superlative: for then the property
will in this respect have been property of man has not rendered the
property correctly stated. Thus (e.g.) inasmuch as he in the
superlative, the property would in who states 'a naturally civilized
animal' as a this respect have been correctly stated.

                              Book VI
                                 1

  THE discussion of Definitions falls into five parts. For you have to
show either (1) that it is not true at all to apply the expression
as well to that to which the term is applied (for the definition of
Man ought to be true of every man); or (2) that though the object
has a genus, he has failed to put the object defined into the genus,
or to put it into the appropriate genus (for the framer of a
definition should first place the object in its genus, and then append
its differences: for of all the elements of the definition the genus
is usually supposed to be the principal mark of the essence of what is
defined): or (3) that the expression is not peculiar to the object
(for, as we said above as well, a definition ought to be peculiar): or
else (4) see if, though he has observed all the aforesaid cautions, he
has yet failed to define the object, that is, to express its
essence. (5) It remains, apart from the foregoing, to see if he has
defined it, but defined it incorrectly.
  Whether, then, the expression be not also true of that of which
the term is true you should proceed to examine according to the
commonplace rules that relate to Accident. For there too the
question is always 'Is so and so true or untrue?': for whenever we
argue that an accident belongs, we declare it to be true, while
whenever we argue that it does not belong, we declare it to be untrue.
If, again, he has failed to place the object in the appropriate genus,
or if the expression be not peculiar to the object, we must go on to
examine the case according to the commonplace rules that relate to
genus and property.
  It remains, then, to prescribe how to investigate whether the object
has been either not defined at all, or else defined incorrectly.
First, then, we must proceed to examine if it has been defined
incorrectly: for with anything it is easier to do it than to do it
correctly. Clearly, then, more mistakes are made in the latter task on
account of its greater difficulty. Accordingly the attack becomes
easier in the latter case than in the former.
  Incorrectness falls into two branches: (1) first, the use of obscure
language (for the language of a definition ought to be the very
clearest possible, seeing that the whole purpose of rendering it is to
make something known); (secondly, if the expression used be longer
than is necessary: for all additional matter in a definition is
superfluous. Again, each of the aforesaid branches is divided into a
number of others.

                                 2

  One commonplace rule, then, in regard to obscurity is, See if the
meaning intended by the definition involves an ambiguity with any
other, e.g. 'Becoming is a passage into being', or 'Health is the
balance of hot and cold elements'. Here 'passage' and 'balance' are
ambiguous terms: it is accordingly not clear which of the several
possible senses of the term he intends to convey. Likewise also, if
the term defined be used in different senses and he has spoken without
distinguishing between them: for then it is not clear to which of them
the definition rendered applies, and one can then bring a captious
objection on the ground that the definition does not apply to all
the things whose definition he has rendered: and this kind of thing is
particularly easy in the case where the definer does not see the
ambiguity of his terms. Or, again, the questioner may himself
distinguish the various senses of the term rendered in the definition,
and then institute his argument against each: for if the expression
used be not adequate to the subject in any of its senses, it is
clear that he cannot have defined it in any sense aright.
  Another rule is, See if he has used a metaphorical expression, as,
for instance, if he has defined knowledge as 'unsupplantable', or
the earth as a 'nurse', or temperance as a 'harmony'. For a
metaphorical expression is always obscure. It is possible, also, to
argue sophistically against the user of a metaphorical expression as
though he had used it in its literal sense: for the definition
stated will not apply to the term defined, e.g. in the case of
temperance: for harmony is always found between notes. Moreover, if
harmony be the genus of temperance, then the same object will occur in
two genera of which neither contains the other: for harmony does not
contain virtue, nor virtue harmony. Again, see if he uses terms that
are unfamiliar, as when Plato describes the eye as 'brow-shaded', or a
certain spider as poison-fanged', or the marrow as 'boneformed'. For
an unusual phrase is always obscure.
  Sometimes a phrase is used neither ambiguously, nor yet
metaphorically, nor yet literally, as when the law is said to be the
'measure' or 'image' of the things that are by nature just. Such
phrases are worse than metaphor; for the latter does make its
meaning to some extent clear because of the likeness involved; for
those who use metaphors do so always in view of some likeness: whereas
this kind of phrase makes nothing clear; for there is no likeness to
justify the description 'measure' or 'image', as applied to the law,
nor is the law ordinarily so called in a literal sense. So then, if
a man says that the law is literally a 'measure' or an 'image', he
speaks falsely: for an image is something produced by imitation, and
this is not found in the case of the law. If, on the other hand, he
does not mean the term literally, it is clear that he has used an
unclear expression, and one that is worse than any sort of
metaphorical expression.
  Moreover, see if from the expression used the definition of the
contrary be not clear; for definitions that have been correctly
rendered also indicate their contraries as well. Or, again, see if,
when it is merely stated by itself, it is not evident what it defines:
just as in the works of the old painters, unless there were an
inscription, the figures used to be unrecognizable.

                                 3
  If, then, the definition be not clear, you should proceed to examine
on lines such as these. If, on the other hand, he has phrased the
definition redundantly, first of all look and see whether he has
used any attribute that belongs universally, either to real objects in
general, or to all that fall under the same genus as the object
defined: for the mention of this is sure to be redundant. For the
genus ought to divide the object from things in general, and the
differentia from any of the things contained in the same genus. Now
any term that belongs to everything separates off the given object
from absolutely nothing, while any that belongs to all the things that
fall under the same genus does not separate it off from the things
contained in the same genus. Any addition, then, of that kind will
be pointless.
  Or see if, though the additional matter may be peculiar to the given
term, yet even when it is struck out the rest of the expression too is
peculiar and makes clear the essence of the term. Thus, in the
definition of man, the addition 'capable of receiving knowledge' is
superfluous; for strike it out, and still the expression is peculiar
and makes clear his essence. Speaking generally, everything is
superfluous upon whose removal the remainder still makes the term that
is being defined clear. Such, for instance, would also be the
definition of the soul, assuming it to be stated as a 'self-moving
number'; for the soul is just 'the self-moving', as Plato defined
it. Or perhaps the expression used, though appropriate, yet does not
declare the essence, if the word 'number' be eliminated. Which of
the two is the real state of the case it is difficult to determine
clearly: the right way to treat the matter in all cases is to be
guided by convenience. Thus (e.g.) it is said that the definition of
phlegm is the 'undigested moisture that comes first off food'. Here
the addition of the word 'undigested' is superfluous, seeing that 'the
first' is one and not many, so that even when undigested' is left
out the definition will still be peculiar to the subject: for it is
impossible that both phlegm and also something else should both be the
first to arise from the food. Or perhaps the phlegm is not
absolutely the first thing to come off the food, but only the first of
the undigested matters, so that the addition 'undigested' is required;
for stated the other way the definition would not be true unless the
phlegm comes first of all.
  Moreover, see if anything contained in the definition fails to apply
to everything that falls under the same species: for this sort of
definition is worse than those which include an attribute belonging to
all things universally. For in that case, if the remainder of the
expression be peculiar, the whole too will be peculiar: for absolutely
always, if to something peculiar anything whatever that is true be
added, the whole too becomes peculiar. Whereas if any part of the
expression do not apply to everything that falls under the same
species, it is impossible that the expression as a whole should be
peculiar: for it will not be predicated convertibly with the object;
e.g. 'a walking biped animal six feet high': for an expression of that
kind is not predicated convertibly with the term, because the
attribute 'six feet high' does not belong to everything that falls
under the same species.
  Again, see if he has said the same thing more than once, saying
(e.g.) 'desire' is a 'conation for the pleasant'. For 'desire' is
always 'for the pleasant', so that what is the same as desire will
also be 'for the pleasant'. Accordingly our definition of desire
becomes 'conation-for-the-pleasant': for the word 'desire' is the
exact equivalent of the words 'conation for-the-pleasant', so that
both alike will be 'for the pleasant'. Or perhaps there is no
absurdity in this; for consider this instance:-Man is a biped':
therefore, what is the same as man is a biped: but 'a walking biped
animal' is the same as man, and therefore walking biped animal is a
biped'. But this involves no real absurdity. For 'biped' is not a
predicate of 'walking animal': if it were, then we should certainly
have 'biped' predicated twice of the same thing; but as a matter of
fact the subject said to be a biped is'a walking biped animal', so
that the word 'biped' is only used as a predicate once. Likewise
also in the case of 'desire' as well: for it is not 'conation' that is
said to be 'for the pleasant', but rather the whole idea, so that
there too the predication is only made once. Absurdity results, not
when the same word is uttered twice, but when the same thing is more
than once predicated of a subject; e.g. if he says, like Xenocrates,
that wisdom defines and contemplates reality:' for definition is a
certain type of contemplation, so that by adding the words 'and
contemplates' over again he says the same thing twice over.
Likewise, too, those fail who say that 'cooling' is 'the privation
of natural heat'. For all privation is a privation of some natural
attribute, so that the addition of the word 'natural' is
superfluous: it would have been enough to say 'privation of heat', for
the word 'privation' shows of itself that the heat meant is natural
heat.
  Again, see if a universal have been mentioned and then a
particular case of it be added as well, e.g. 'Equity is a remission of
what is expedient and just'; for what is just is a branch of what is
expedient and is therefore included in the latter term: its mention is
therefore redundant, an addition of the particular after the universal
has been already stated. So also, if he defines 'medicine' as
'knowledge of what makes for health in animals and men', or 'the
law' as 'the image of what is by nature noble and just'; for what is
just is a branch of what is noble, so that he says the same thing more
than once.

                                 4

  Whether, then, a man defines a thing correctly or incorrectly you
should proceed to examine on these and similar lines. But whether he
has mentioned and defined its essence or no, should be examined as
follows: First of all, see if he has failed to make the definition
through terms that are prior and more intelligible. For the reason why
the definition is rendered is to make known the term stated, and we
make things known by taking not any random terms, but such as are
prior and more intelligible, as is done in demonstrations (for so it
is with all teaching and learning); accordingly, it is clear that a
man who does not define through terms of this kind has not defined
at all. Otherwise, there will be more than one definition of the
same thing: for clearly he who defines through terms that are prior
and more intelligible has also framed a definition, and a better
one, so that both would then be definitions of the same object. This
sort of view, however, does not generally find acceptance: for of each
real object the essence is single: if, then, there are to be a
number of definitions of the same thing, the essence of the object
will be the same as it is represented to be in each of the
definitions, and these representations are not the same, inasmuch as
the definitions are different. Clearly, then, any one who has not
defined a thing through terms that are prior and more intelligible has
not defined it at all.
  The statement that a definition has not been made through more
intelligible terms may be understood in two senses, either supposing
that its terms are absolutely less intelligible, or supposing that
they are less intelligible to us: for either sense is possible. Thus
absolutely the prior is more intelligible than the posterior, a point,
for instance, than a line, a line than a plane, and a plane than a
solid; just as also a unit is more intelligible than a number; for
it is the prius and starting-point of all number. Likewise, also, a
letter is more intelligible than a syllable. Whereas to us it
sometimes happens that the converse is the case: for the solid falls
under perception most of all-more than a plane-and a plane more than a
line, and a line more than a point; for most people learn things
like the former earlier than the latter; for any ordinary intelligence
can grasp them, whereas the others require an exact and exceptional
understanding.
  Absolutely, then, it is better to try to make what is posterior
known through what is prior, inasmuch as such a way of procedure is
more scientific. Of course, in dealing with persons who cannot
recognize things through terms of that kind, it may perhaps be
necessary to frame the expression through terms that are
intelligible to them. Among definitions of this kind are those of a
point, a line, and a plane, all of which explain the prior by the
posterior; for they say that a point is the limit of a line, a line of
a plane, a plane of a solid. One must, however, not fail to observe
that those who define in this way cannot show the essential nature
of the term they define, unless it so happens that the same thing is
more intelligible both to us and also absolutely, since a correct
definition must define a thing through its genus and its differentiae,
and these belong to the order of things which are absolutely more
intelligible than, and prior to, the species. For annul the genus
and differentia, and the species too is annulled, so that these are
prior to the species. They are also more intelligible; for if the
species be known, the genus and differentia must of necessity be known
as well (for any one who knows what a man is knows also what
'animal' and 'walking' are), whereas if the genus or the differentia
be known it does not follow of necessity that the species is known
as well: thus the species is less intelligible. Moreover, those who
say that such definitions, viz. those which proceed from what is
intelligible to this, that, or the other man, are really and truly
definitions, will have to say that there are several definitions of
one and the same thing. For, as it happens, different things are
more intelligible to different people, not the same things to all; and
so a different definition would have to be rendered to each several
person, if the definition is to be constructed from what is more
intelligible to particular individuals. Moreover, to the same people
different things are more intelligible at different times; first of
all the objects of sense; then, as they become more sharpwitted, the
converse; so that those who hold that a definition ought to be
rendered through what is more intelligible to particular individuals
would not have to render the same definition at all times even to
the same person. It is clear, then, that the right way to define is
not through terms of that kind, but through what is absolutely more
intelligible: for only in this way could the definition come always to
be one and the same. Perhaps, also, what is absolutely intelligible is
what is intelligible, not to all, but to those who are in a sound
state of understanding, just as what is absolutely healthy is what
is healthy to those in a sound state of body. All such points as
this ought to be made very precise, and made use of in the course of
discussion as occasion requires. The demolition of a definition will
most surely win a general approval if the definer happens to have
framed his expression neither from what is absolutely more
intelligible nor yet from what is so to us.
  One form, then, of the failure to work through more intelligible
terms is the exhibition of the prior through the posterior, as we
remarked before.' Another form occurs if we find that the definition
has been rendered of what is at rest and definite through what is
indefinite and in motion: for what is still and definite is prior to
what is indefinite and in motion.
  Of the failure to use terms that are prior there are three forms:
  (1) The first is when an opposite has been defined through its
opposite, e.g.i. good through evil: for opposites are always
simultaneous by nature. Some people think, also, that both are objects
of the same science, so that the one is not even more intelligible
than the other. One must, however, observe that it is perhaps not
possible to define some things in any other way, e.g. the double
without the half, and all the terms that are essentially relative: for
in all such cases the essential being is the same as a certain
relation to something, so that it is impossible to understand the
one term without the other, and accordingly in the definition of the
one the other too must be embraced. One ought to learn up all such
points as these, and use them as occasion may seem to require.
  (2) Another is-if he has used the term defined itself. This passes
unobserved when the actual name of the object is not used, e.g.
supposing any one had defined the sun as a star that appears by
day'. For in bringing in 'day' he brings in the sun. To detect
errors of this sort, exchange the word for its definition, e.g. the
definition of 'day' as the 'passage of the sun over the earth'.
Clearly, whoever has said 'the passage of the sun over the earth'
has said 'the sun', so that in bringing in the 'day' he has brought in
the sun.
  (3) Again, see if he has defined one coordinate member of a division
by another, e.g. 'an odd number' as 'that which is greater by one than
an even number'. For the co-ordinate members of a division that are
derived from the same genus are simultaneous by nature and 'odd' and
'even' are such terms: for both are differentiae of number.
  Likewise also, see if he has defined a superior through a
subordinate term, e.g. 'An "even number" is "a number divisible into
halves"', or '"the good" is a "state of virtue" '. For 'half' is
derived from 'two', and 'two' is an even number: virtue also is a kind
of good, so that the latter terms are subordinate to the former.
Moreover, in using the subordinate term one is bound to use the
other as well: for whoever employs the term 'virtue' employs the
term 'good', seeing that virtue is a certain kind of good: likewise,
also, whoever employs the term 'half' employs the term 'even', for
to be 'divided in half' means to be divided into two, and two is even.

                                 5

  Generally speaking, then, one commonplace rule relates to the
failure to frame the expression by means of terms that are prior and
more intelligible: and of this the subdivisions are those specified
above. A second is, see whether, though the object is in a genus, it
has not been placed in a genus. This sort of error is always found
where the essence of the object does not stand first in the
expression, e.g. the definition of 'body' as 'that which has three
dimensions', or the definition of 'man', supposing any one to give it,
as 'that which knows how to count': for it is not stated what it is
that has three dimensions, or what it is that knows how to count:
whereas the genus is meant to indicate just this, and is submitted
first of the terms in the definition.
  Moreover, see if, while the term to be defined is used in relation
to many things, he has failed to render it in relation to all of them;
as (e.g.) if he define 'grammar' as the 'knowledge how to write from
dictation': for he ought also to say that it is a knowledge how to
read as well. For in rendering it as 'knowledge of writing' has no
more defined it than by rendering it as 'knowledge of reading':
neither in fact has succeeded, but only he who mentions both these
things, since it is impossible that there should be more than one
definition of the same thing. It is only, however, in some cases
that what has been said corresponds to the actual state of things:
in some it does not, e.g. all those terms which are not used
essentially in relation to both things: as medicine is said to deal
with the production of disease and health; for it is said
essentially to do the latter, but the former only by accident: for
it is absolutely alien to medicine to produce disease. Here, then, the
man who renders medicine as relative to both of these things has not
defined it any better than he who mentions the one only. In fact he
has done it perhaps worse, for any one else besides the doctor is
capable of producing disease.
  Moreover, in a case where the term to be defined is used in relation
to several things, see if he has rendered it as relative to the
worse rather than to the better; for every form of knowledge and
potentiality is generally thought to be relative to the best.
  Again, if the thing in question be not placed in its own proper
genus, one must examine it according to the elementary rules in regard
to genera, as has been said before.'
  Moreover, see if he uses language which transgresses the genera of
the things he defines, defining, e.g. justice as a 'state that
produces equality' or 'distributes what is equal': for by defining
it so he passes outside the sphere of virtue, and so by leaving out
the genus of justice he fails to express its essence: for the
essence of a thing must in each case bring in its genus. It is the
same thing if the object be not put into its nearest genus; for the
man who puts it into the nearest one has stated all the higher genera,
seeing that all the higher genera are predicated of the lower. Either,
then, it ought to be put into its nearest genus, or else to the higher
genus all the differentiae ought to be appended whereby the nearest
genus is defined. For then he would not have left out anything: but
would merely have mentioned the subordinate genus by an expression
instead of by name. On the other hand, he who mentions merely the
higher genus by itself, does not state the subordinate genus as
well: in saying 'plant' a man does not specify 'a tree'.

                                 6

  Again, in regard to the differentiae, we must examine in like manner
whether the differentiae, too, that he has stated be those of the
genus. For if a man has not defined the object by the differentiae
peculiar to it, or has mentioned something such as is utterly
incapable of being a differentia of anything, e.g. 'animal' or
'substance', clearly he has not defined it at all: for the aforesaid
terms do not differentiate anything at all. Further, we must see
whether the differentia stated possesses anything that is
co-ordinate with it in a division; for, if not, clearly the one stated
could not be a differentia of the genus. For a genus is always divided
by differentiae that are co-ordinate members of a division, as, for
instance, by the terms 'walking', 'flying', 'aquatic', and 'biped'. Or
see if, though the contrasted differentia exists, it yet is not true
of the genus, for then, clearly, neither of them could be a
differentia of the genus; for differentiae that are co-ordinates in
a division with the differentia of a thing are all true of the genus
to which the thing belongs. Likewise, also, see if, though it be true,
yet the addition of it to the genus fails to make a species. For then,
clearly, this could not be a specific differentia of the genus: for
a specific differentia, if added to the genus, always makes a species.
If, however, this be no true differentia, no more is the one
adduced, seeing that it is a co-ordinate member of a division with
this.
  Moreover, see if he divides the genus by a negation, as those do who
define line as 'length without breadth': for this means simply that it
has not any breadth. The genus will then be found to partake of its
own species: for, since of everything either an affirmation or its
negation is true, length must always either lack breadth or possess
it, so that 'length' as well, i.e. the genus of 'line', will be either
with or without breadth. But 'length without breadth' is the
definition of a species, as also is 'length with breadth': for
'without breadth' and 'with breadth' are differentiae, and the genus
and differentia constitute the definition of the species. Hence the
genus would admit of the definition of its species. Likewise, also, it
will admit of the definition of the differentia, seeing that one or
the other of the aforesaid differentiae is of necessity predicated
of the genus. The usefulness of this principle is found in meeting
those who assert the existence of 'Ideas': for if absolute length
exist, how will it be predicable of the genus that it has breadth or
that it lacks it? For one assertion or the other will have to be
true of 'length' universally, if it is to be true of the genus at all:
and this is contrary to the fact: for there exist both lengths which
have, and lengths which have not, breadth. Hence the only people
against whom the rule can be employed are those who assert that a
genus is always numerically one; and this is what is done by those who
assert the real existence of the 'Ideas'; for they allege that
absolute length and absolute animal are the genus.
  It may be that in some cases the definer is obliged to employ a
negation as well, e.g. in defining privations. For 'blind' means a
thing which cannot see when its nature is to see. There is no
difference between dividing the genus by a negation, and dividing it
by such an affirmation as is bound to have a negation as its
co-ordinate in a division, e.g. supposing he had defined something
as 'length possessed of breadth'; for co-ordinate in the division with
that which is possessed of breadth is that which possesses no
breadth and that only, so that again the genus is divided by a
negation.
  Again, see if he rendered the species as a differentia, as do
those who define 'contumely' as 'insolence accompanied by jeering';
for jeering is a kind of insolence, i.e. it is a species and not a
differentia.
  Moreover, see if he has stated the genus as the differentia, e.g.
'Virtue is a good or noble state: for 'good' is the genus of 'virtue'.
Or possibly 'good' here is not the genus but the differentia, on the
principle that the same thing cannot be in two genera of which neither
contains the other: for 'good' does not include 'state', nor vice
versa: for not every state is good nor every good a 'state'. Both,
then, could not be genera, and consequently, if 'state' is the genus
of virtue, clearly 'good' cannot be its genus: it must rather be the
differentia'. Moreover, 'a state' indicates the essence of virtue,
whereas 'good' indicates not the essence but a quality: and to
indicate a quality is generally held to be the function of the
differentia. See, further, whether the differentia rendered
indicates an individual rather than a quality: for the general view is
that the differentia always expresses a quality.
  Look and see, further, whether the differentia belongs only by
accident to the object defined. For the differentia is never an
accidental attribute, any more than the genus is: for the
differentia of a thing cannot both belong and not belong to it.
  Moreover, if either the differentia or the species, or any of the
things which are under the species, is predicable of the genus, then
he could not have defined the term. For none of the aforesaid can
possibly be predicated of the genus, seeing that the genus is the term
with the widest range of all. Again, see if the genus be predicated of
the differentia; for the general view is that the genus is predicated,
not of the differentia, but of the objects of which the differentia is
predicated. Animal (e.g.) is predicated of 'man' or 'ox' or other
walking animals, not of the actual differentia itself which we
predicate of the species. For if 'animal' is to be predicated of
each of its differentiae, then 'animal' would be predicated of the
species several times over; for the differentiae are predicates of the
species. Moreover, the differentiae will be all either species or
individuals, if they are animals; for every animal is either a species
or an individual.
  Likewise you must inquire also if the species or any of the
objects that come under it is predicated of the differentia: for
this is impossible, seeing that the differentia is a term with a wider
range than the various species. Moreover, if any of the species be
predicated of it, the result will be that the differentia is a
species: if, for instance, 'man' be predicated, the differentia is
clearly the human race. Again, see if the differentia fails to be
prior to the species: for the differentia ought to be posterior to the
genus, but prior to the species.
  Look and see also if the differentia mentioned belongs to a
different genus, neither contained in nor containing the genus in
question. For the general view is that the same differentia cannot
be used of two non-subaltern genera. Else the result will be that
the same species as well will be in two non-subaltern genera: for each
of the differentiae imports its own genus, e.g. 'walking' and
'biped' import with them the genus 'animal'. If, then, each of the
genera as well is true of that of which the differentia is true, it
clearly follows that the species must be in two non-subaltern
genera. Or perhaps it is not impossible for the same differentia to be
used of two non-subaltern genera, and we ought to add the words
'except they both be subordinate members of the same genus'. Thus
'walking animal' and 'flying animal' are non-subaltern genera, and
'biped' is the differentia of both. The words 'except they both be
subordinate members of the same genus' ought therefore to be added;
for both these are subordinate to 'animal'. From this possibility,
that the same differentia may be used of two non-subaltern genera,
it is clear also that there is no necessity for the differentia to
carry with it the whole of the genus to which it belongs, but only the
one or the other of its limbs together with the genera that are higher
than this, as 'biped' carries with it either 'flying' or 'walking
animal'.
  See, too, if he has rendered 'existence in' something as the
differentia of a thing's essence: for the general view is that
locality cannot differentiate between one essence and another.
Hence, too, people condemn those who divide animals by means of the
terms 'walking' and 'aquatic', on the ground that 'walking' and
'aquatic' indicate mere locality. Or possibly in this case the censure
is undeserved; for 'aquatic' does not mean 'in' anything; nor does
it denote a locality, but a certain quality: for even if the thing
be on the dry land, still it is aquatic: and likewise a land-animal,
even though it be in the water, will still be a and not an
aquatic-animal. But all the same, if ever the differentia does
denote existence in something, clearly he will have made a bad
mistake.
  Again, see if he has rendered an affection as the differentia: for
every affection, if intensified, subverts the essence of the thing,
while the differentia is not of that kind: for the differentia is
generally considered rather to preserve that which it
differentiates; and it is absolutely impossible for a thing to exist
without its own special differentia: for if there be no 'walking',
there will be no 'man'. In fact, we may lay down absolutely that a
thing cannot have as its differentia anything in respect of which it
is subject to alteration: for all things of that kind, if intensified,
destroy its essence. If, then, a man has rendered any differentia of
this kind, he has made a mistake: for we undergo absolutely no
alteration in respect of our differentiae.
  Again, see if he has failed to render the differentia of a
relative term relatively to something else; for the differentiae of
relative terms are themselves relative, as in the case also of
knowledge. This is classed as speculative, practical and productive;
and each of these denotes a relation: for it speculates upon
something, and produces something and does something.
  Look and see also if the definer renders each relative term
relatively to its natural purpose: for while in some cases the
particular relative term can be used in relation to its natural
purpose only and to nothing else, some can be used in relation to
something else as well. Thus sight can only be used for seeing, but
a strigil can also be used to dip up water. Still, if any one were
to define a strigil as an instrument for dipping water, he has made
a mistake: for that is not its natural function. The definition of a
thing's natural function is 'that for which it would be used by the
prudent man, acting as such, and by the science that deals specially
with that thing'.
  Or see if, whenever a term happens to be used in a number of
relations, he has failed to introduce it in its primary relation: e.g.
by defining 'wisdom' as the virtue of 'man' or of the 'soul,' rather
than of the 'reasoning faculty': for 'wisdom' is the virtue
primarily of the reasoning faculty: for it is in virtue of this that
both the man and his soul are said to be wise.
  Moreover, if the thing of which the term defined has been stated
to be an affection or disposition, or whatever it may be, be unable to
admit it, the definer has made a mistake. For every disposition and
every affection is formed naturally in that of which it is an
affection or disposition, as knowledge, too, is formed in the soul,
being a disposition of soul. Sometimes, however, people make bad
mistakes in matters of this sort, e.g. all those who say that
'sleep' is a 'failure of sensation', or that 'perplexity' is a state
of 'equality between contrary reasonings', or that 'pain' is a
'violent disruption of parts that are naturally conjoined'. For
sleep is not an attribute of sensation, whereas it ought to be, if
it is a failure of sensation. Likewise, perplexity is not an attribute
of opposite reasonings, nor pain of parts naturally conjoined: for
then inanimate things will be in pain, since pain will be present in
them. Similar in character, too, is the definition of 'health', say,
as a 'balance of hot and cold elements': for then health will be
necessarily exhibited by the hot and cold elements: for balance of
anything is an attribute inherent in those things of which it is the
balance, so that health would be an attribute of them. Moreover,
people who define in this way put effect for cause, or cause for
effect. For the disruption of parts naturally conjoined is not pain,
but only a cause of pain: nor again is a failure of sensation sleep,
but the one is the cause of the other: for either we go to sleep
because sensation fails, or sensation fails because we go to sleep.
Likewise also an equality between contrary reasonings would be
generally considered to be a cause of perplexity: for it is when we
reflect on both sides of a question and find everything alike to be in
keeping with either course that we are perplexed which of the two we
are to do.
  Moreover, with regard to all periods of time look and see whether
there be any discrepancy between the differentia and the thing
defined: e.g. supposing the 'immortal' to be defined as a 'living
thing immune at present from destruction'. For a living thing that
is immune 'at present' from destruction will be immortal 'at present'.
Possibly, indeed, in this case this result does not follow, owing to
the ambiguity of the words 'immune at present from destruction': for
it may mean either that the thing has not been destroyed at present,
or that it cannot be destroyed at present, or that at present it is
such that it never can be destroyed. Whenever, then, we say that a
living thing is at present immune from destruction, we mean that it is
at present a living thing of such a kind as never to be destroyed: and
this is equivalent to saying that it is immortal, so that it is not
meant that it is immortal only at present. Still, if ever it does
happen that what has been rendered according to the definition belongs
in the present only or past, whereas what is meant by the word does
not so belong, then the two could not be the same. So, then, this
commonplace rule ought to be followed, as we have said.

                                 7

  You should look and see also whether the term being defined is
applied in consideration of something other than the definition
rendered. Suppose (e.g.) a definition of 'justice' as the 'ability
to distribute what is equal'. This would not be right, for 'just'
describes rather the man who chooses, than the man who is able to
distribute what is equal: so that justice could not be an ability to
distribute what is equal: for then also the most just man would be the
man with the most ability to distribute what is equal.
  Moreover, see if the thing admits of degrees, whereas what is
rendered according to the definition does not, or, vice versa, what is
rendered according to the definition admits of degrees while the thing
does not. For either both must admit them or else neither, if indeed
what is rendered according to the definition is the same as the thing.
Moreover, see if, while both of them admit of degrees, they yet do not
both become greater together: e.g. suppose sexual love to be the
desire for intercourse: for he who is more intensely in love has not a
more intense desire for intercourse, so that both do not become
intensified at once: they certainly should, however, had they been the
same thing.
  Moreover, suppose two things to be before you, see if the term to be
defined applies more particularly to the one to which the content of
the definition is less applicable. Take, for instance, the
definition of 'fire' as the 'body that consists of the most rarefied
particles'. For 'fire' denotes flame rather than light, but flame is
less the body that consists of the most rarefied particles than is
light: whereas both ought to be more applicable to the same thing,
if they had been the same. Again, see if the one expression applies
alike to both the objects before you, while the other does not apply
to both alike, but more particularly to one of them.
  Moreover, see if he renders the definition relative to two things
taken separately: thus, the beautiful' is 'what is pleasant to the
eyes or to the ears": or 'the real' is 'what is capable of being acted
upon or of acting'. For then the same thing will be both beautiful and
not beautiful, and likewise will be both real and not real. For
'pleasant to the ears' will be the same as 'beautiful', so that 'not
pleasant to the ears' will be the same as 'not beautiful': for of
identical things the opposites, too, are identical, and the opposite
of 'beautiful' is 'not beautiful', while of 'pleasant to the ears' the
opposite is not pleasant to the cars': clearly, then, 'not pleasant to
the ears' is the same thing as 'not beautiful'. If, therefore,
something be pleasant to the eyes but not to the ears, it will be both
beautiful and not beautiful. In like manner we shall show also that
the same thing is both real and unreal.
  Moreover, of both genera and differentiae and all the other terms
rendered in definitions you should frame definitions in lieu of the
terms, and then see if there be any discrepancy between them.

                                 8

  If the term defined be relative, either in itself or in respect of
its genus, see whether the definition fails to mention that to which
the term, either in itself or in respect of its genus, is relative,
e.g. if he has defined 'knowledge' as an 'incontrovertible conception'
or 'wishing' as 'painless conation'. For of everything relative the
essence is relative to something else, seeing that the being of
every relative term is identical with being in a certain relation to
something. He ought, therefore, to have said that knowledge is
'conception of a knowable' and that wishing is 'conation for a
good'. Likewise, also, if he has defined 'grammar' as 'knowledge of
letters': whereas in the definition there ought to be rendered
either the thing to which the term itself is relative, or that,
whatever it is, to which its genus is relative. Or see if a relative
term has been described not in relation to its end, the end in
anything being whatever is best in it or gives its purpose to the
rest. Certainly it is what is best or final that should be stated,
e.g. that desire is not for the pleasant but for pleasure: for this is
our purpose in choosing what is pleasant as well.
  Look and see also if that in relation to which he has rendered the
term be a process or an activity: for nothing of that kind is an
end, for the completion of the activity or process is the end rather
than the process or activity itself. Or perhaps this rule is not
true in all cases, for almost everybody prefers the present experience
of pleasure to its cessation, so that they would count the activity as
the end rather than its completion.
  Again see in some cases if he has failed to distinguish the quantity
or quality or place or other differentiae of an object; e.g. the
quality and quantity of the honour the striving for which makes a
man ambitious: for all men strive for honour, so that it is not enough
to define the ambitious man as him who strives for honour, but the
aforesaid differentiae must be added. Likewise, also, in defining
the covetous man the quantity of money he aims at, or in the case of
the incontinent man the quality of the pleasures, should be stated.
For it is not the man who gives way to any sort of pleasure whatever
who is called incontinent, but only he who gives way to a certain kind
of pleasure. Or again, people sometimes define night as a 'shadow on
the earth', or an earthquake as a movement of the earth', or a cloud
as 'condensation of the air', or a wind as a 'movement of the air';
whereas they ought to specify as well quantity, quality, place, and
cause. Likewise, also, in other cases of the kind: for by omitting any
differentiae whatever he fails to state the essence of the term. One
should always attack deficiency. For a movement of the earth does
not constitute an earthquake, nor a movement of the air a wind,
irrespective of its manner and the amount involved.
  Moreover, in the case of conations, and in any other cases where
it applies, see if the word 'apparent' is left out, e.g. 'wishing is a
conation after the good', or 'desire is a conation after the
pleasant'-instead of saying 'the apparently good', or 'pleasant'.
For often those who exhibit the conation do not perceive what is
good or pleasant, so that their aim need not be really good or
pleasant, but only apparently so. They ought, therefore, to have
rendered the definition also accordingly. On the other hand, any one
who maintains the existence of Ideas ought to be brought face to
face with his Ideas, even though he does render the word in
question: for there can be no Idea of anything merely apparent: the
general view is that an Idea is always spoken of in relation to an
Idea: thus absolute desire is for the absolutely pleasant, and
absolute wishing is for the absolutely good; they therefore cannot
be for an apparent good or an apparently pleasant: for the existence
of an absolutely-apparently-good or pleasant would be an absurdity.

                                 9

  Moreover, if the definition be of the state of anything, look at
what is in the state, while if it be of what is in the state, look
at the state: and likewise also in other cases of the kind. Thus if
the pleasant be identical with the beneficial, then, too, the man
who is pleased is benefited. Speaking generally, in definitions of
this sort it happens that what the definer defines is in a sense
more than one thing: for in defining knowledge, a man in a sense
defines ignorance as well, and likewise also what has knowledge and
what lacks it, and what it is to know and to be ignorant. For if the
first be made clear, the others become in a certain sense clear as
well. We have, then, to be on our guard in all such cases against
discrepancy, using the elementary principles drawn from
consideration of contraries and of coordinates.
  Moreover, in the case of relative terms, see if the species is
rendered as relative to a species of that to which the genus is
rendered as relative, e.g. supposing belief to be relative to some
object of belief, see whether a particular belief is made relative
to some particular object of belief: and, if a multiple be relative to
a fraction, see whether a particular multiple be made relative to a
particular fraction. For if it be not so rendered, clearly a mistake
has been made.
  See, also, if the opposite of the term has the opposite
definition, whether (e.g.) the definition of 'half' is the opposite of
that of 'double': for if 'double' is 'that which exceeds another by an
equal amount to that other', 'half' is 'that which is exceeded by an
amount equal to itself'. In the same way, too, with contraries. For to
the contrary term will apply the definition that is contrary in some
one of the ways in which contraries are conjoined. Thus (e.g.) if
'useful'='productive of good', 'injurious'=productive of evil' or
'destructive of good', for one or the other of thee is bound to be
contrary to the term originally used. Suppose, then, neither of
these things to be the contrary of the term originally used, then
clearly neither of the definitions rendered later could be the
definition of the contrary of the term originally defined: and
therefore the definition originally rendered of the original term
has not been rightly rendered either. Seeing, moreover, that of
contraries, the one is sometimes a word forced to denote the privation
of the other, as (e.g.) inequality is generally held to be the
privation of equality (for 'unequal' merely describes things that
are not equal'), it is therefore clear that that contrary whose form
denotes the privation must of necessity be defined through the
other; whereas the other cannot then be defined through the one
whose form denotes the privation; for else we should find that each is
being interpreted by the other. We must in the case of contrary
terms keep an eye on this mistake, e.g. supposing any one were to
define equality as the contrary of inequality: for then he is defining
it through the term which denotes privation of it. Moreover, a man who
so defines is bound to use in his definition the very term he is
defining; and this becomes clear, if for the word we substitute its
definition. For to say 'inequality' is the same as to say 'privation
of equality'. Therefore equality so defined will be 'the contrary of
the privation of equality', so that he would have used the very word
to be defined. Suppose, however, that neither of the contraries be
so formed as to denote privation, but yet the definition of it be
rendered in a manner like the above, e.g. suppose 'good' to be defined
as 'the contrary of evil', then, since it is clear that 'evil' too
will be 'the contrary of good' (for the definition of things that
are contrary in this must be rendered in a like manner), the result
again is that he uses the very term being defined: for 'good' is
inherent in the definition of 'evil'. If, then, 'good' be the contrary
of evil, and evil be nothing other than the 'contrary of good', then
'good' will be the 'contrary of the contrary of good'. Clearly,
then, he has used the very word to be defined.
  Moreover, see if in rendering a term formed to denote privation,
he has failed to render the term of which it is the privation, e.g.
the state, or contrary, or whatever it may be whose privation it is:
also if he has omitted to add either any term at all in which the
privation is naturally formed, or else that in which it is naturally
formed primarily, e.g. whether in defining 'ignorance' a privation
he has failed to say that it is the privation of 'knowledge'; or has
failed to add in what it is naturally formed, or, though he has
added this, has failed to render the thing in which it is primarily
formed, placing it (e.g.) in 'man' or in 'the soul', and not in the
'reasoning faculty': for if in any of these respects he fails, he
has made a mistake. Likewise, also, if he has failed to say that
'blindness' is the 'privation of sight in an eye': for a proper
rendering of its essence must state both of what it is the privation
and what it is that is deprived.
  Examine further whether he has defined by the expression 'a
privation' a term that is not used to denote a privation: thus a
mistake of this sort also would be generally thought to be incurred in
the case of 'error' by any one who is not using it as a merely
negative term. For what is generally thought to be in error is not
that which has no knowledge, but rather that which has been
deceived, and for this reason we do not talk of inanimate things or of
children as 'erring'. 'Error', then, is not used to denote a mere
privation of knowledge.

                                10

  Moreover, see whether the like inflexions in the definition apply to
the like inflexions of the term; e.g. if 'beneficial' means
'productive of health', does 'beneficially' mean productively of
health' and a 'benefactor' a 'producer of health'?
  Look too and see whether the definition given will apply to the Idea
as well. For in some cases it will not do so; e.g. in the Platonic
definition where he adds the word 'mortal' in his definitions of
living creatures: for the Idea (e.g. the absolute Man) is not
mortal, so that the definition will not fit the Idea. So always
wherever the words 'capable of acting on' or 'capable of being acted
upon' are added, the definition and the Idea are absolutely bound to
be discrepant: for those who assert the existence of Ideas hold that
they are incapable of being acted upon, or of motion. In dealing
with these people even arguments of this kind are useful.
  Further, see if he has rendered a single common definition of
terms that are used ambiguously. For terms whose definition
corresponding their common name is one and the same, are synonymous;
if, then, the definition applies in a like manner to the whole range
of the ambiguous term, it is not true of any one of the objects
described by the term. This is, moreover, what happens to Dionysius'
definition of 'life' when stated as 'a movement of a creature
sustained by nutriment, congenitally present with it': for this is
found in plants as much as in animals, whereas 'life' is generally
understood to mean not one kind of thing only, but to be one thing
in animals and another in plants. It is possible to hold the view that
life is a synonymous term and is always used to describe one thing
only, and therefore to render the definition in this way on purpose:
or it may quite well happen that a man may see the ambiguous character
of the word, and wish to render the definition of the one sense
only, and yet fail to see that he has rendered a definition common
to both senses instead of one peculiar to the sense he intends. In
either case, whichever course he pursues, he is equally at fault.
Since ambiguous terms sometimes pass unobserved, it is best in
questioning to treat such terms as though they were synonymous (for
the definition of the one sense will not apply to the other, so that
the answerer will be generally thought not to have defined it
correctly, for to a synonymous term the definition should apply in its
full range), whereas in answering you should yourself distinguish
between the senses. Further, as some answerers call 'ambiguous' what
is really synonymous, whenever the definition rendered fails to
apply universally, and, vice versa, call synonymous what is really
ambiguous supposing their definition applies to both senses of the
term, one should secure a preliminary admission on such points, or
else prove beforehand that so-and-so is ambiguous or synonymous, as
the case may be: for people are more ready to agree when they do not
foresee what the consequence will be. If, however, no admission has
been made, and the man asserts that what is really synonymous is
ambiguous because the definition he has rendered will not apply to the
second sense as well, see if the definition of this second meaning
applies also to the other meanings: for if so, this meaning must
clearly be synonymous with those others. Otherwise, there will be more
than one definition of those other meanings, for there are
applicable to them two distinct definitions in explanation of the
term, viz. the one previously rendered and also the later one.
Again, if any one were to define a term used in several senses, and,
finding that his definition does not apply to them all, were to
contend not that the term is ambiguous, but that even the term does
not properly apply to all those senses, just because his definition
will not do so either, then one may retort to such a man that though
in some things one must not use the language of the people, yet in a
question of terminology one is bound to employ the received and
traditional usage and not to upset matters of that sort.

                                11

  Suppose now that a definition has been rendered of some complex
term, take away the definition of one of the elements in the
complex, and see if also the rest of the definition defines the rest
of it: if not, it is clear that neither does the whole definition
define the whole complex. Suppose, e.g. that some one has defined a
'finite straight line' as 'the limit of a finite plane, such that
its centre is in a line with its extremes'; if now the definition of a
finite line' be the 'limit of a finite plane', the rest (viz. 'such
that its centre is in a line with its extremes') ought to be a
definition of straight'. But an infinite straight line has neither
centre nor extremes and yet is straight so that this remainder does
not define the remainder of the term.
  Moreover, if the term defined be a compound notion, see if the
definition rendered be equimembral with the term defined. A definition
is said to be equimembral with the term defined when the number of the
elements compounded in the latter is the same as the number of nouns
and verbs in the definition. For the exchange in such cases is bound
to be merely one of term for term, in the case of some if not of
all, seeing that there are no more terms used now than formerly;
whereas in a definition terms ought to be rendered by phrases, if
possible in every case, or if not, in the majority. For at that
rate, simple objects too could be defined by merely calling them by
a different name, e.g. 'cloak' instead of 'doublet'.
  The mistake is even worse, if actually a less well known term be
substituted, e.g. 'pellucid mortal' for 'white man': for it is no
definition, and moreover is less intelligible when put in that form.
  Look and see also whether, in the exchange of words, the sense fails
still to be the same. Take, for instance, the explanation of
'speculative knowledge' as 'speculative conception': for conception is
not the same as knowledge-as it certainly ought to be if the whole
is to be the same too: for though the word 'speculative' is common
to both expressions, yet the remainder is different.
  Moreover, see if in replacing one of the terms by something else
he has exchanged the genus and not the differentia, as in the
example just given: for 'speculative' is a less familiar term than
knowledge; for the one is the genus and the other the differentia, and
the genus is always the most familiar term of all; so that it is not
this, but the differentia, that ought to have been changed, seeing
that it is the less familiar. It might be held that this criticism
is ridiculous: because there is no reason why the most familiar term
should not describe the differentia, and not the genus; in which case,
clearly, the term to be altered would also be that denoting the
genus and not the differentia. If, however, a man is substituting
for a term not merely another term but a phrase, clearly it is of
the differentia rather than of the genus that a definition should be
rendered, seeing that the object of rendering the definition is to
make the subject familiar; for the differentia is less familiar than
the genus.
  If he has rendered the definition of the differentia, see whether
the definition rendered is common to it and something else as well:
e.g. whenever he says that an odd number is a 'number with a
middle', further definition is required of how it has a middle: for
the word 'number' is common to both expressions, and it is the word
'odd' for which the phrase has been substituted. Now both a line and a
body have a middle, yet they are not 'odd'; so that this could not
be a definition of 'odd'. If, on the other hand, the phrase 'with a
middle' be used in several senses, the sense here intended requires to
be defined. So that this will either discredit the definition or prove
that it is no definition at all.

                                12

  Again, see if the term of which he renders the definition is a
reality, whereas what is contained in the definition is not, e.g.
Suppose 'white' to be defined as 'colour mingled with fire': for
what is bodiless cannot be mingled with body, so that 'colour'
'mingled with fire' could not exist, whereas 'white' does exist.
  Moreover, those who in the case of relative terms do not distinguish
to what the object is related, but have described it only so as to
include it among too large a number of things, are wrong either wholly
or in part; e.g. suppose some one to have defined 'medicine' as a
science of Reality'. For if medicine be not a science of anything that
is real, the definition is clearly altogether false; while if it be
a science of some real thing, but not of another, it is partly
false; for it ought to hold of all reality, if it is said to be of
Reality essentially and not accidentally: as is the case with other
relative terms: for every object of knowledge is a term relative to
knowledge: likewise, also, with other relative terms, inasmuch as
all such are convertible. Moreover, if the right way to render account
of a thing be to render it as it is not in itself but accidentally,
then each and every relative term would be used in relation not to one
thing but to a number of things. For there is no reason why the same
thing should not be both real and white and good, so that it would
be a correct rendering to render the object in relation to any one
whatsoever of these, if to render what it is accidentally be a correct
way to render it. It is, moreover, impossible that a definition of
this sort should be peculiar to the term rendered: for not only but
the majority of the other sciences too, have for their object some
real thing, so that each will be a science of reality. Clearly,
then, such a definition does not define any science at all; for a
definition ought to be peculiar to its own term, not general.
  Sometimes, again, people define not the thing but only the thing
in a good or perfect condition. Such is the definition of a
rhetorician as 'one who can always see what will persuade in the given
circumstances, and omit nothing'; or of a thief, as 'one who pilfers
in secret': for clearly, if they each do this, then the one will be
a good rhetorician, and the other a good thief: whereas it is not
the actual pilfering in secret, but the wish to do it, that
constitutes the thief.
  Again, see if he has rendered what is desirable for its own sake
as desirable for what it produces or does, or as in any way
desirable because of something else, e.g. by saying that justice is
'what preserves the laws' or that wisdom is 'what produces happiness';
for what produces or preserves something else is one of the things
desirable for something else. It might be said that it is possible for
what is desirable in itself to be desirable for something else as
well: but still to define what is desirable in itself in such a way is
none the less wrong: for the essence contains par excellence what is
best in anything, and it is better for a thing to be desirable in
itself than to be desirable for something else, so that this is rather
what the definition too ought to have indicated.

                                13

  See also whether in defining anything a man has defined it as an
'A and B', or as a 'product of A and B' or as an 'A+B'. If he
defines it as and B', the definition will be true of both and yet of
neither of them; suppose, e.g. justice to be defined as 'temperance
and courage.' For if of two persons each has one of the two only, both
and yet neither will be just: for both together have justice, and
yet each singly fails to have it. Even if the situation here described
does not so far appear very absurd because of the occurrence of this
kind of thing in other cases also (for it is quite possible for two
men to have a mina between them, though neither of them has it by
himself), yet least that they should have contrary attributes surely
seems quite absurd; and yet this will follow if the one be temperate
and yet a coward, and the other, though brave, be a profligate; for
then both will exhibit both justice and injustice: for if justice be
temperance and bravery, then injustice will be cowardice and
profligacy. In general, too, all the ways of showing that the whole is
not the same as the sum of its parts are useful in meeting the type
just described; for a man who defines in this way seems to assert that
the parts are the same as the whole. The arguments are particularly
appropriate in cases where the process of putting the parts together
is obvious, as in a house and other things of that sort: for there,
clearly, you may have the parts and yet not have the whole, so that
parts and whole cannot be the same.
  If, however, he has said that the term being defined is not 'A and
B' but the 'product of A and B', look and see in the first place if
A and B cannot in the nature of things have a single product: for some
things are so related to one another that nothing can come of them,
e.g. a line and a number. Moreover, see if the term that has been
defined is in the nature of things found primarily in some single
subject, whereas the things which he has said produce it are not found
primarily in any single subject, but each in a separate one. If so,
clearly that term could not be the product of these things: for the
whole is bound to be in the same things wherein its parts are, so that
the whole will then be found primarily not in one subject only, but in
a number of them. If, on the other hand, both parts and whole are
found primarily in some single subject, see if that medium is not
the same, but one thing in the case of the whole and another in that
of the parts. Again, see whether the parts perish together with the
whole: for it ought to happen, vice versa, that the whole perishes
when the parts perish; when the whole perishes, there is no
necessity that the parts should perish too. Or again, see if the whole
be good or evil, and the parts neither, or, vice versa, if the parts
be good or evil and the whole neither. For it is impossible either for
a neutral thing to produce something good or bad, or for things good
or bad to produce a neutral thing. Or again, see if the one thing is
more distinctly good than the other is evil, and yet the product be no
more good than evil, e.g. suppose shamelessness be defined as 'the
product of courage and false opinion': here the goodness of courage
exceeds the evil of false opinion; accordingly the product of these
ought to have corresponded to this excess, and to be either good
without qualification, or at least more good than evil. Or it may be
that this does not necessarily follow, unless each be in itself good
or bad; for many things that are productive are not good in
themselves, but only in combination; or, per contra, they are good
taken singly, and bad or neutral in combination. What has just been
said is most clearly illustrated in the case of things that make for
health or sickness; for some drugs are such that each taken alone is
good, but if they are both administered in a mixture, bad.
  Again, see whether the whole, as produced from a better and worse,
fails to be worse than the better and better than the worse element.
This again, however, need not necessarily be the case, unless the
elements compounded be in themselves good; if they are not, the
whole may very well not be good, as in the cases just instanced.
  Moreover, see if the whole be synonymous with one of the elements:
for it ought not to be, any more than in the case of syllables: for
the syllable is not synonymous with any of the letters of which it
is made up.
  Moreover, see if he has failed to state the manner of their
composition: for the mere mention of its elements is not enough to
make the thing intelligible. For the essence of any compound thing
is not merely that it is a product of so-and-so, but that it is a
product of them compounded in such and such a way, just as in the case
of a house: for here the materials do not make a house irrespective of
the way they are put together.
  If a man has defined an object as 'A+B', the first thing to be
said is that 'A+B' means the same either as 'A and B', or as the
'product of A and B.' for 'honey+water' means either the honey and the
water, or the 'drink made of honey and water'. If, then, he admits
that 'A+B' is + B' is the same as either of these two things, the same
criticisms will apply as have already been given for meeting each of
them. Moreover, distinguish between the different senses in which
one thing may be said to be '+' another, and see if there is none of
them in which A could be said to exist '+ B.' Thus e.g. supposing
the expression to mean that they exist either in some identical
thing capable of containing them (as e.g. justice and courage are
found in the soul), or else in the same place or in the same time, and
if this be in no way true of the A and B in question, clearly the
definition rendered could not hold of anything, as there is no
possible way in which A can exist B'. If, however, among the various
senses above distinguished, it be true that A and B are each found
in the same time as the other, look and see if possibly the two are
not used in the same relation. Thus e.g. suppose courage to have
been defined as 'daring with right reasoning': here it is possible
that the person exhibits daring in robbery, and right reasoning in
regard to the means of health: but he may have 'the former quality+the
latter' at the same time, and not as yet be courageous! Moreover, even
though both be used in the same relation as well, e.g. in relation
to medical treatment (for a man may exhibit both daring and right
reasoning in respect of medical treatment), still, none the less,
not even this combination of 'the one+the other 'makes him
'courageous'. For the two must not relate to any casual object that is
the same, any more than each to a different object; rather, they
must relate to the function of courage, e.g. meeting the perils of
war, or whatever is more properly speaking its function than this.
  Some definitions rendered in this form fail to come under the
aforesaid division at all, e.g. a definition of anger as 'pain with
a consciousness of being slighted'. For what this means to say is that
it is because of a consciousness of this sort that the pain occurs;
but to occur 'because of' a thing is not the same as to occur '+ a
thing' in any of its aforesaid senses.

                                14

  Again, if he have described the whole compounded as the
'composition' of these things (e.g. 'a living creature' as a
'composition of soul and body'), first of all see whether he has
omitted to state the kind of composition, as (e.g.) in a definition of
'flesh' or 'bone' as the 'composition of fire, earth, and air'. For it
is not enough to say it is a composition, but you should also go on to
define the kind of composition: for these things do not form flesh
irrespective of the manner of their composition, but when compounded
in one way they form flesh, when in another, bone. It appears,
moreover, that neither of the aforesaid substances is the same as a
'composition' at all: for a composition always has a decomposition
as its contrary, whereas neither of the aforesaid has any contrary.
Moreover, if it is equally probable that every compound is a
composition or else that none is, and every kind of living creature,
though a compound, is never a composition, then no other compound
could be a composition either.
  Again, if in the nature of a thing two contraries are equally liable
to occur, and the thing has been defined through the one, clearly it
has not been defined; else there will be more than one definition of
the same thing; for how is it any more a definition to define it
through this one than through the other, seeing that both alike are
naturally liable to occur in it? Such is the definition of the soul,
if defined as a substance capable of receiving knowledge: for it has a
like capacity for receiving ignorance.
  Also, even when one cannot attack the definition as a whole for lack
of acquaintance with the whole, one should attack some part of it,
if one knows that part and sees it to be incorrectly rendered: for
if the part be demolished, so too is the whole definition. Where,
again, a definition is obscure, one should first of all correct and
reshape it in order to make some part of it clear and get a handle for
attack, and then proceed to examine it. For the answerer is bound
either to accept the sense as taken by the questioner, or else himself
to explain clearly whatever it is that his definition means. Moreover,
just as in the assemblies the ordinary practice is to move an
emendation of the existing law and, if the emendation is better,
they repeal the existing law, so one ought to do in the case of
definitions as well: one ought oneself to propose a second definition:
for if it is seen to be better, and more indicative of the object
defined, clearly the definition already laid down will have been
demolished, on the principle that there cannot be more than one
definition of the same thing.
  In combating definitions it is always one of the chief elementary
principles to take by oneself a happy shot at a definition of the
object before one, or to adopt some correctly expressed definition.
For one is bound, with the model (as it were) before one's eyes, to
discern both any shortcoming in any features that the definition ought
to have, and also any superfluous addition, so that one is better
supplied with lines of attack.
  As to definitions, then, let so much suffice.

                              Book VII
                                 1

  WHETHER two things are 'the same' or 'different', in the most
literal of the meanings ascribed to 'sameness' (and we said' that 'the
same' applies in the most literal sense to what is numerically one),
may be examined in the light of their inflexions and coordinates and
opposites. For if justice be the same as courage, then too the just
man is the same as the brave man, and 'justly' is the same as
'bravely'. Likewise, too, in the case of their opposites: for if two
things be the same, their opposites also will be the same, in any of
the recognized forms of opposition. For it is the same thing to take
the opposite of the one or that of the other, seeing that they are the
same. Again it may be examined in the light of those things which tend
to produce or to destroy the things in question of their formation and
destruction, and in general of any thing that is related in like
manner to each. For where things are absolutely the same, their
formations and destructions also are the same, and so are the things
that tend to produce or to destroy them. Look and see also, in a
case where one of two things is said to be something or other in a
superlative degree, if the other of these alleged identical things can
also be described by a superlative in the same respect. Thus
Xenocrates argues that the happy life and the good life are the
same, seeing that of all forms of life the good life is the most
desirable and so also is the happy life: for 'the most desirable'
and the greatest' apply but to one thing.' Likewise also in other
cases of the kind. Each, however, of the two things termed
'greatest' or most desirable' must be numerically one: otherwise no
proof will have been given that they are the same; for it does not
follow because Peloponnesians and Spartans are the bravest of the
Greeks, that Peloponnesians are the same as Spartans, seeing that
'Peloponnesian' is not any one person nor yet 'Spartan'; it only
follows that the one must be included under the other as 'Spartans'
are under 'Peloponnesians': for otherwise, if the one class be not
included under the other, each will be better than the other. For then
the Peloponnesians are bound to be better than the Spartans, seeing
that the one class is not included under the other; for they are
better than anybody else. Likewise also the Spartans must perforce
be better than the Peloponnesians; for they too are better than
anybody else; each then is better than the other! Clearly therefore
what is styled 'best' and 'greatest' must be a single thing, if it
is to be proved to be 'the same' as another. This also is why
Xenocrates fails to prove his case: for the happy life is not
numerically single, nor yet the good life, so that it does not
follow that, because they are both the most desirable, they are
therefore the same, but only that the one falls under the other.
  Again, look and see if, supposing the one to be the same as
something, the other also is the same as it: for if they be not both
the same as the same thing, clearly neither are they the same as one
another.
  Moreover, examine them in the light of their accidents or of the
things of which they are accidents: for any accident belonging to
the one must belong also to the other, and if the one belong to
anything as an accident, so must the other also. If in any of these
respects there is a discrepancy, clearly they are not the same.
  See further whether, instead of both being found in one class of
predicates, the one signifies a quality and the other a quantity or
relation. Again, see if the genus of each be not the same, the one
being 'good' and the other evil', or the one being 'virtue' and the
other 'knowledge': or see if, though the genus is the same, the
differentiae predicted of either be not the same, the one (e.g.) being
distinguished as a 'speculative' science, the other as a 'practical'
science. Likewise also in other cases.
  Moreover, from the point of view of 'degrees', see if the one admits
an increase of degree but not the other, or if though both admit it,
they do not admit it at the same time; just as it is not the case that
a man desires intercourse more intensely, the more intensely he is
in love, so that love and the desire for intercourse are not the same.
  Moreover, examine them by means of an addition, and see whether
the addition of each to the same thing fails to make the same whole;
or if the subtraction of the same thing from each leaves a different
remainder. Suppose (e.g.) that he has declared 'double a half' to be
the same as 'a multiple of a half': then, subtracting the words 'a
half' from each, the remainders ought to have signified the same
thing: but they do not; for 'double' and 'a multiple of' do not
signify the same thing.
  Inquire also not only if some impossible consequence results
directly from the statement made, that A and B are the same, but
also whether it is possible for a supposition to bring it about; as
happens to those who assert that 'empty' is the same as 'full of air':
for clearly if the air be exhausted, the vessel will not be less but
more empty, though it will no longer be full of air. So that by a
supposition, which may be true or may be false (it makes no difference
which), the one character is annulled and not the other, showing
that they are not the same.
  Speaking generally, one ought to be on the look-out for any
discrepancy anywhere in any sort of predicate of each term, and in the
things of which they are predicated. For all that is predicated of the
one should be predicated also of the other, and of whatever the one is
a predicate, the other should be a predicate of it as well.
  Moreover, as 'sameness' is a term used in many senses, see whether
things that are the same in one way are the same also in a different
way. For there is either no necessity or even no possibility that
things that are the same specifically or generically should be
numerically the same, and it is with the question whether they are
or are not the same in that sense that we are concerned.
  Moreover, see whether the one can exist without the other; for, if
so, they could not be the same.

                                 2

  Such is the number of the commonplace rules that relate to
'sameness'. It is clear from what has been said that all the
destructive commonplaces relating to sameness are useful also in
questions of definition, as was said before:' for if what is signified
by the term and by the expression be not the same, clearly the
expression rendered could not be a definition. None of the
constructive commonplaces, on the other hand, helps in the matter of
definition; for it is not enough to show the sameness of content
between the expression and the term, in order to establish that the
former is a definition, but a definition must have also all the
other characters already announced.

                                 3

  This then is the way, and these the arguments, whereby the attempt
to demolish a definition should always be made. If, on the other hand,
we desire to establish one, the first thing to observe is that few
if any who engage in discussion arrive at a definition by reasoning:
they always assume something of the kind as their starting points-both
in geometry and in arithmetic and the other studies of that kind. In
the second place, to say accurately what a definition is, and how it
should be given, belongs to another inquiry. At present it concerns us
only so far as is required for our present purpose, and accordingly we
need only make the bare statement that to reason to a thing's
definition and essence is quite possible. For if a definition is an
expression signifying the essence of the thing and the predicates
contained therein ought also to be the only ones which are
predicated of the thing in the category of essence; and genera and
differentiae are so predicated in that category: it is obvious that if
one were to get an admission that so and so are the only attributes
predicated in that category, the expression containing so and so would
of necessity be a definition; for it is impossible that anything
else should be a definition, seeing that there is not anything else
predicated of the thing in the category of essence.
  That a definition may thus be reached by a process of reasoning is
obvious. The means whereby it should be established have been more
precisely defined elsewhere, but for the purposes of the inquiry now
before us the same commonplace rules serve. For we have to examine
into the contraries and other opposites of the thing, surveying the
expressions used both as wholes and in detail: for if the opposite
definition defines that opposite term, the definition given must of
necessity be that of the term before us. Seeing, however, that
contraries may be conjoined in more than one way, we have to select
from those contraries the one whose contrary definition seems most
obvious. The expressions, then, have to be examined each as a whole in
the way we have said, and also in detail as follows. First of all, see
that the genus rendered is correctly rendered; for if the contrary
thing be found in the contrary genus to that stated in the definition,
and the thing before you is not in that same genus, then it would
clearly be in the contrary genus: for contraries must of necessity
be either in the same genus or in contrary genera. The differentiae,
too, that are predicated of contraries we expect to be contrary,
e.g. those of white and black, for the one tends to pierce the vision,
while the other tends to compress it. So that if contrary differentiae
to those in the definition are predicated of the contrary term, then
those rendered in the definition would be predicated of the term
before us. Seeing, then, that both the genus and the differentiae have
been rightly rendered, clearly the expression given must be the
right definition. It might be replied that there is no necessity why
contrary differentiae should be predicated of contraries, unless the
contraries be found within the same genus: of things whose genera
are themselves contraries it may very well be that the same
differentia is used of both, e.g. of justice and injustice; for the
one is a virtue and the other a vice of the soul: 'of the soul',
therefore, is the differentia in both cases, seeing that the body as
well has its virtue and vice. But this much at least is true, that the
differentiae of contraries are either contrary or else the same. If,
then, the contrary differentia to that given be predicated of the
contrary term and not of the one in hand, clearly the differentia
stated must be predicated of the latter. Speaking generally, seeing
that the definition consists of genus and differentiae, if the
definition of the contrary term be apparent, the definition of the
term before you will be apparent also: for since its contrary is found
either in the same genus or in the contrary genus, and likewise also
the differentiae predicated of opposites are either contrary to, or
the same as, each other, clearly of the term before you there will
be predicated either the same genus as of its contrary, while, of
its differentiae, either all are contrary to those of its contrary, or
at least some of them are so while the rest remain the same; or,
vice versa, the differentiae will be the same and the genera contrary;
or both genera and differentiae will be contrary. And that is all; for
that both should be the same is not possible; else contraries will
have the same definition.
  Moreover, look at it from the point of view of its inflexions and
coordinates. For genera and definitions are bound to correspond in
either case. Thus if forgetfulness be the loss of knowledge, to forget
is to lose knowledge, and to have forgotten is to have lost knowledge.
If, then, any one whatever of these is agreed to, the others must of
necessity be agreed to as well. Likewise, also, if destruction is
the decomposition of the thing's essence, then to be destroyed is to
have its essence decomposed, and 'destructively' means 'in such a
way as to decompose its essence'; if again 'destructive' means 'apt to
decompose something's essence', then also 'destruction' means 'the
decomposition of its essence'. Likewise also with the rest: an
admission of any one of them whatever, and all the rest are admitted
too.
    Moreover, look at it from the point of view of things that stand
in relations that are like each other. For if 'healthy' means
'productive of health', 'vigorous' too will mean 'productive of
vigour', and 'useful' will mean 'productive of good.' For each of
these things is related in like manner to its own peculiar end, so
that if one of them is defined as 'productive of' that end, this
will also be the definition of each of the rest as well.
    Moreover, look at it from the point of and like degrees, in all
the ways in which it is possible to establish a result by comparing
two and two together. Thus if A defines a better than B defines and
B is a definition of so too is A of a. Further, if A's claim to define
a is like B's to define B, and B defines B, then A too defines a. This
examination from the point of view of greater degrees is of no use
when a single definition is compared with two things, or two
definitions with one thing; for there cannot possibly be one
definition of two things or two of the same thing.

                                 4

  The most handy of all the commonplace arguments are those just
mentioned and those from co-ordinates and inflexions, and these
therefore are those which it is most important to master and to have
ready to hand: for they are the most useful on the greatest number
of occasions. Of the rest, too, the most important are those of most
general application: for these are the most effective, e.g. that you
should examine the individual cases, and then look to see in the
case of their various species whether the definition applies. For
the species is synonymous with its individuals. This sort of inquiry
is of service against those who assume the existence of Ideas, as
has been said before.' Moreover see if a man has used a term
metaphorically, or predicated it of itself as though it were something
different. So too if any other of the commonplace rules is of
general application and effective, it should be employed.

                                 5

  That it is more difficult to establish than to overthrow a
definition, is obvious from considerations presently to be urged.
For to see for oneself, and to secure from those whom one is
questioning, an admission of premisses of this sort is no simple
matter, e.g. that of the elements of the definition rendered the one
is genus and the other differentia, and that only the genus and
differentiae are predicated in the category of essence. Yet without
these premisses it is impossible to reason to a definition; for if any
other things as well are predicated of the thing in the category of
essence, there is no telling whether the formula stated or some
other one is its definition, for a definition is an expression
indicating the essence of a thing. The point is clear also from the
following: It is easier to draw one conclusion than many. Now in
demolishing a definition it is sufficient to argue against one point
only (for if we have overthrown any single point whatsoever, we
shall have demolished the definition); whereas in establishing a
definition, one is bound to bring people to the view that everything
contained in the definition is attributable. Moreover, in establishing
a case, the reasoning brought forward must be universal: for the
definition put forward must be predicated of everything of which the
term is predicated, and must moreover be convertible, if the
definition rendered is to be peculiar to the subject. In
overthrowing a view, on the other hand, there is no longer any
necessity to show one's point universally: for it is enough to show
that the formula is untrue of any one of the things embraced under the
term.
  Further, even supposing it should be necessary to overthrow
something by a universal proposition, not even so is there any need to
prove the converse of the proposition in the process of overthrowing
the definition. For merely to show that the definition fails to be
predicated of every one of the things of which the term is predicated,
is enough to overthrow it universally: and there is no need to prove
the converse of this in order to show that the term is predicated of
things of which the expression is not predicated. Moreover, even if it
applies to everything embraced under the term, but not to it alone,
the definition is thereby demolished.
  The case stands likewise in regard to the property and genus of a
term also. For in both cases it is easier to overthrow than to
establish. As regards the property this is clear from what has been
said: for as a rule the property is rendered in a complex phrase, so
that to overthrow it, it is only necessary to demolish one of the
terms used, whereas to establish it is necessary to reason to them
all. Then, too, nearly all the other rules that apply to the
definition will apply also to the property of a thing. For in
establishing a property one has to show that it is true of
everything included under the term in question, whereas to overthrow
one it is enough to show in a single case only that it fails to
belong: further, even if it belongs to everything falling under the
term, but not to that only, it is overthrown in this case as well,
as was explained in the case of the definition. In regard to the
genus, it is clear that you are bound to establish it in one way only,
viz. by showing that it belongs in every case, while of overthrowing
it there are two ways: for if it has been shown that it belongs either
never or not in a certain case, the original statement has been
demolished. Moreover, in establishing a genus it is not enough to show
that it belongs, but also that it belongs as genus has to be shown;
whereas in overthrowing it, it is enough to show its failure to belong
either in some particular case or in every case. It appears, in
fact, as though, just as in other things to destroy is easier than
to create, so in these matters too to overthrow is easier than to
establish.
  In the case of an accidental attribute the universal proposition
is easier to overthrow than to establish; for to establish it, one has
to show that it belongs in every case, whereas to overthrow it, it
is enough to show that it does not belong in one single case. The
particular proposition is, on the contrary, easier to establish than
to overthrow: for to establish it, it is enough to show that it
belongs in a particular instance, whereas to overthrow it, it has to
be shown that it never belongs at all.
  It is clear also that the easiest thing of all is to overthrow a
definition. For on account of the number of statements involved we are
presented in the definition with the greatest number of points for
attack, and the more plentiful the material, the quicker an argument
comes: for there is more likelihood of a mistake occurring in a
large than in a small number of things. Moreover, the other rules
too may be used as means for attacking a definition: for if either the
formula be not peculiar, or the genus rendered be the wrong one, or
something included in the formula fail to belong, the definition is
thereby demolished. On the other hand, against the others we cannot
bring all of the arguments drawn from definitions, nor yet of the
rest: for only those relating to accidental attributes apply generally
to all the aforesaid kinds of attribute. For while each of the
aforesaid kinds of attribute must belong to the thing in question, yet
the genus may very well not belong as a property without as yet
being thereby demolished. Likewise also the property need not belong
as a genus, nor the accident as a genus or property, so long as they
do belong. So that it is impossible to use one set as a basis of
attack upon the other except in the case of definition. Clearly, then,
it is the easiest of all things to demolish a definition, while to
establish one is the hardest. For there one both has to establish
all those other points by reasoning (i.e. that the attributes stated
belong, and that the genus rendered is the true genus, and that the
formula is peculiar to the term), and moreover, besides this, that the
formula indicates the essence of the thing; and this has to be done
correctly.
  Of the rest, the property is most nearly of this kind: for it is
easier to demolish, because as a rule it contains several terms; while
it is the hardest to establish, both because of the number of things
that people must be brought to accept, and, besides this, because it
belongs to its subject alone and is predicated convertibly with its
subject.
  The easiest thing of all to establish is an accidental predicate:
for in other cases one has to show not only that the predicate
belongs, but also that it belongs in such and such a particular way:
whereas in the case of the accident it is enough to show merely that
it belongs. On the other hand, an accidental predicate is the
hardest thing to overthrow, because it affords the least material: for
in stating accident a man does not add how the predicate belongs;
and accordingly, while in other cases it is possible to demolish
what is said in two ways, by showing either that the predicate does
not belong, or that it does not belong in the particular way stated,
in the case of an accidental predicate the only way to demolish it
is to show that it does not belong at all.
  The commonplace arguments through which we shall be well supplied
with lines of argument with regard to our several problems have now
been enumerated at about sufficient length.

                              Book VIII
                                 1

  NEXT there fall to be discussed the problems of arrangement and
method in pitting questions. Any one who intends to frame questions
must, first of all, select the ground from which he should make his
attack; secondly, he must frame them and arrange them one by one to
himself; thirdly and lastly, he must proceed actually to put them to
the other party. Now so far as the selection of his ground is
concerned the problem is one alike for the philosopher and the
dialectician; but how to go on to arrange his points and frame his
questions concerns the dialectician only: for in every problem of that
kind a reference to another party is involved. Not so with the
philosopher, and the man who is investigating by himself: the
premisses of his reasoning, although true and familiar, may be refused
by the answerer because they lie too near the original statement and
so he foresees what will follow if he grants them: but for this the
philosopher does not care. Nay, he may possibly be even anxious to
secure axioms as familiar and as near to the question in hand as
possible: for these are the bases on which scientific reasonings are
built up.
  The sources from which one's commonplace arguments should be drawn
have already been described:' we have now to discuss the arrangement
and formation of questions and first to distinguish the premisses,
other than the necessary premisses, which have to be adopted. By
necessary premisses are meant those through which the actual reasoning
is constructed. Those which are secured other than these are of four
kinds; they serve either inductively to secure the universal premiss
being granted, or to lend weight to the argument, or to conceal the
conclusion, or to render the argument more clear. Beside these there
is no other premiss which need be secured: these are the ones
whereby you should try to multiply and formulate your questions. Those
which are used to conceal the conclusion serve a controversial purpose
only; but inasmuch as an undertaking of this sort is always
conducted against another person, we are obliged to employ them as
well.
  The necessary premisses through which the reasoning is effected,
ought not to be propounded directly in so many words. Rather one
should soar as far aloof from them as possible. Thus if one desires to
secure an admission that the knowledge of contraries is one, one
should ask him to admit it not of contraries, but of opposites: for,
if he grants this, one will then argue that the knowledge of
contraries is also the same, seeing that contraries are opposites;
if he does not, one should secure the admission by induction, by
formulating a proposition to that effect in the case of some
particular pair of contraries. For one must secure the necessary
premisses either by reasoning or by induction, or else partly by one
and partly by the other, although any propositions which are too
obvious to be denied may be formulated in so many words. This is
because the coming conclusion is less easily discerned at the
greater distance and in the process of induction, while at the same
time, even if one cannot reach the required premisses in this way,
it is still open to one to formulate them in so many words. The
premisses, other than these, that were mentioned above, must be
secured with a view to the latter. The way to employ them respectively
is as follows: Induction should proceed from individual cases to the
universal and from the known to the unknown; and the objects of
perception are better known, to most people if not invariably.
Concealment of one's plan is obtained by securing through
prosyllogisms the premisses through which the proof of the original
proposition is going to be constructed-and as many of them as
possible. This is likely to be effected by making syllogisms to
prove not only the necessary premisses but also some of those which
are required to establish them. Moreover, do not state the conclusions
of these premisses but draw them later one after another; for this
is likely to keep the answerer at the greatest possible distance
from the original proposition. Speaking generally, a man who desires
to get information by a concealed method should so put his questions
that when he has put his whole argument and has stated the conclusion,
people still ask 'Well, but why is that?' This result will be
secured best of all by the method above described: for if one states
only the final conclusion, it is unclear how it comes about; for the
answerer does not foresee on what grounds it is based, because the
previous syllogisms have not been made articulate to him: while the
final syllogism, showing the conclusion, is likely to be kept least
articulate if we lay down not the secured propositions on which it
is based, but only the grounds on which we reason to them.
  It is a useful rule, too, not to secure the admissions claimed as
the bases of the syllogisms in their proper order, but alternately
those that conduce to one conclusion and those that conduce to
another; for, if those which go together are set side by side, the
conclusion that will result from them is more obvious in advance.
  One should also, wherever possible, secure the universal premiss
by a definition relating not to the precise terms themselves but to
their co-ordinates; for people deceive themselves, whenever the
definition is taken in regard to a co-ordinate, into thinking that
they are not making the admission universally. An instance would be,
supposing one had to secure the admission that the angry man desires
vengeance on account of an apparent slight, and were to secure this,
that 'anger' is a desire for vengeance on account of an apparent
slight: for, clearly, if this were secured, we should have universally
what we intend. If, on the other hand, people formulate propositions
relating to the actual terms themselves, they often find that the
answerer refuses to grant them because on the actual term itself he is
readier with his objection, e.g. that the 'angry man' does not
desire vengeance, because we become angry with our parents, but we
do not desire vengeance on them. Very likely the objection is not
valid; for upon some people it is vengeance enough to cause them
pain and make them sorry; but still it gives a certain plausibility
and air of reasonableness to the denial of the proposition. In the
case, however, of the definition of 'anger' it is not so easy to
find an objection.
  Moreover, formulate your proposition as though you did so not for
its own sake, but in order to get at something else: for people are
shy of granting what an opponent's case really requires. Speaking
generally, a questioner should leave it as far as possible doubtful
whether he wishes to secure an admission of his proposition or of
its opposite: for if it be uncertain what their opponent's argument
requires, people are more ready to say what they themselves think.
  Moreover, try to secure admissions by means of likeness: for such
admissions are plausible, and the universal involved is less patent;
e.g. make the other person admit that as knowledge and ignorance of
contraries is the same, so too perception of contraries is the same;
or vice versa, that since the perception is the same, so is the
knowledge also. This argument resembles induction, but is not the same
thing; for in induction it is the universal whose admission is secured
from the particulars, whereas in arguments from likeness, what is
secured is not the universal under which all the like cases fall.
  It is a good rule also, occasionally to bring an objection against
oneself: for answerers are put off their guard against those who
appear to be arguing impartially. It is useful too, to add that 'So
and so is generally held or commonly said'; for people are shy of
upsetting the received opinion unless they have some positive
objection to urge: and at the same time they are cautious about
upsetting such things because they themselves too find them useful.
Moreover, do not be insistent, even though you really require the
point: for insistence always arouses the more opposition. Further,
formulate your premiss as though it were a mere illustration: for
people admit the more readily a proposition made to serve some other
purpose, and not required on its own account. Moreover, do not
formulate the very proposition you need to secure, but rather
something from which that necessarily follows: for people are more
willing to admit the latter, because it is not so clear from this what
the result will be, and if the one has been secured, the other has
been secured also. Again, one should put last the point which one most
wishes to have conceded; for people are specially inclined to deny the
first questions put to them, because most people in asking questions
put first the points which they are most eager to secure. On the other
hand, in dealing with some people propositions of this sort should
be put forward first: for ill-tempered men admit most readily what
comes first, unless the conclusion that will result actually stares
them in the face, while at the close of an argument they show their
ill-temper. Likewise also with those who consider themselves smart
at answering: for when they have admitted most of what you want they
finally talk clap-trap to the effect that the conclusion does not
follow from their admissions: yet they say 'Yes' readily, confident in
their own character, and imagining that they cannot suffer any
reverse. Moreover, it is well to expand the argument and insert things
that it does not require at all, as do those who draw false
geometrical figures: for in the multitude of details the whereabouts
of the fallacy is obscured. For this reason also a questioner
sometimes evades observation as he adds in a corner what, if he
formulated it by itself, would not be granted.
  For concealment, then, the rules which should be followed are the
above. Ornament is attained by induction and distinction of things
closely akin. What sort of process induction is obvious: as for
distinction, an instance of the kind of thing meant is the distinction
of one form of knowledge as better than another by being either more
accurate, or concerned with better objects; or the distinction of
sciences into speculative, practical, and productive. For everything
of this kind lends additional ornament to the argument, though there
is no necessity to say them, so far as the conclusion goes.
  For clearness, examples and comparisons should be adduced, and let
the illustrations be relevant and drawn from things that we know, as
in Homer and not as in Choerilus; for then the proposition is likely
to become clearer.

                                 2

  In dialectics, syllogism should be employed in reasoning against
dialecticians rather than against the crowd: induction, on the other
hand, is most useful against the crowd. This point has been treated
previously as well.' In induction, it is possible in some cases to ask
the question in its universal form, but in others this is not easy,
because there is no established general term that covers all the
resemblances: in this case, when people need to secure the
universal, they use the phrase 'in all cases of this sort'. But it
is one of the very hardest things to distinguish which of the things
adduced are 'of this sort', and which are not: and in this connexion
people often throw dust in each others' eyes in their discussion,
the one party asserting the likeness of things that are not alike, and
the other disputing the likeness of things that are. One ought,
therefore, to try oneself to coin a word to cover all things of the
given sort, so as to leave no opportunity either to the answerer to
dispute, and say that the thing advanced does not answer to a like
description, or to the questioner to suggest falsely that it does
answer to a like description, for many things appear to answer to like
descriptions that do not really do so.
  If one has made an induction on the strength of several cases and
yet the answerer refuses to grant the universal proposition, then it
is fair to demand his objection. But until one has oneself stated in
what cases it is so, it is not fair to demand that he shall say in
what cases it is not so: for one should make the induction first,
and then demand the objection. One ought, moreover, to claim that
the objections should not be brought in reference to the actual
subject of the proposition, unless that subject happen to be the one
and only thing of the kind, as for instance two is the one prime
number among the even numbers: for, unless he can say that this
subject is unique of its kind, the objector ought to make his
objection in regard to some other. People sometimes object to a
universal proposition, and bring their objection not in regard to
the thing itself, but in regard to some homonym of it: thus they argue
that a man can very well have a colour or a foot or a hand other
than his own, for a painter may have a colour that is not his own, and
a cook may have a foot that is not his own. To meet them, therefore,
you should draw the distinction before putting your question in such
cases: for so long as the ambiguity remains undetected, so long will
the objection to the proposition be deemed valid. If, however, he
checks the series of questions by an objection in regard not to some
homonym, but to the actual thing asserted, the questioner should
withdraw the point objected to, and form the remainder into a
universal proposition, until he secures what he requires; e.g. in
the case of forgetfulness and having forgotten: for people refuse to
admit that the man who has lost his knowledge of a thing has forgotten
it, because if the thing alters, he has lost knowledge of it, but he
has not forgotten it. Accordingly the thing to do is to withdraw the
part objected to, and assert the remainder, e.g. that if a person have
lost knowledge of a thing while it still remains, he then has
forgotten it. One should similarly treat those who object to the
statement that 'the greater the good, the greater the evil that is its
opposite': for they allege that health, which is a less good thing
than vigour, has a greater evil as its opposite: for disease is a
greater evil than debility. In this case too, therefore, we have to
withdraw the point objected to; for when it has been withdrawn, the
man is more likely to admit the proposition, e.g. that 'the greater
good has the greater evil as its opposite, unless the one good
involves the other as well', as vigour involves health. This should be
done not only when he formulates an objection, but also if, without so
doing, he refuses to admit the point because he foresees something
of the kind: for if the point objected to be withdrawn, he will be
forced to admit the proposition because he cannot foresee in the
rest of it any case where it does not hold true: if he refuse to admit
it, then when asked for an objection he certainly will be unable to
render one. Propositions that are partly false and partly true are
of this type: for in the case of these it is possible by withdrawing a
part to leave the rest true. If, however, you formulate the
proposition on the strength of many cases and he has no objection to
bring, you may claim that he shall admit it: for a premiss is valid in
dialectics which thus holds in several instances and to which no
objection is forthcoming.
  Whenever it is possible to reason to the same conclusion either
through or without a reduction per impossibile, if one is
demonstrating and not arguing dialectically it makes no difference
which method of reasoning be adopted, but in argument with another
reasoning per impossibile should be avoided. For where one has
reasoned without the reduction per impossibile, no dispute can
arise; if, on the other hand, one does reason to an impossible
conclusion, unless its falsehood is too plainly manifest, people
deny that it is impossible, so that the questioners do not get what
they want.
  One should put forward all propositions that hold true of several
cases, and to which either no objection whatever appears or at least
not any on the surface: for when people cannot see any case in which
it is not so, they admit it for true.
  The conclusion should not be put in the form of a question; if it
be, and the man shakes his head, it looks as if the reasoning had
failed. For often, even if it be not put as a question but advanced as
a consequence, people deny it, and then those who do not see that it
follows upon the previous admissions do not realize that those who
deny it have been refuted: when, then, the one man merely asks it as a
question without even saying that it so follows, and the other
denies it, it looks altogether as if the reasoning had failed.
  Not every universal question can form a dialectical proposition as
ordinarily understood, e.g. 'What is man?' or 'How many meanings has
"the good"?' For a dialectical premiss must be of a form to which it
is possible to reply 'Yes' or 'No', whereas to the aforesaid it is not
possible. For this reason questions of this kind are not dialectical
unless the questioner himself draws distinctions or divisions before
expressing them, e.g. 'Good means this, or this, does it not?' For
questions of this sort are easily answered by a Yes or a No. Hence one
should endeavour to formulate propositions of this kind in this
form. It is at the same time also perhaps fair to ask the other man
how many meanings of 'the good' there are, whenever you have
yourself distinguished and formulated them, and he will not admit them
at all.
  Any one who keeps on asking one thing for a long time is a bad
inquirer. For if he does so though the person questioned keeps on
answering the questions, clearly he asks a large number of
questions, or else asks the same question a large number of times:
in the one case he merely babbles, in the other he fails to reason:
for reasoning always consists of a small number of premisses. If, on
the other hand, he does it because the person questioned does not
answer the questions, he is at fault in not taking him to task or
breaking off the discussion.

                                 3

  There are certain hypotheses upon which it is at once difficult to
bring, and easy to stand up to, an argument. Such (e.g.) are those
things which stand first and those which stand last in the order of
nature. For the former require definition, while the latter have to be
arrived at through many steps if one wishes to secure a continuous
proof from first principles, or else all discussion about them wears
the air of mere sophistry: for to prove anything is impossible
unless one begins with the appropriate principles, and connects
inference with inference till the last are reached. Now to define
first principles is just what answerers do not care to do, nor do they
pay any attention if the questioner makes a definition: and yet
until it is clear what it is that is proposed, it is not easy to
discuss it. This sort of thing happens particularly in the case of the
first principles: for while the other propositions are shown through
these, these cannot be shown through anything else: we are obliged
to understand every item of that sort by a definition. The inferences,
too, that lie too close to the first principle are hard to treat in
argument: for it is not possible to bring many arguments in regard
to them, because of the small number of those steps, between the
conclusion and the principle, whereby the succeeding propositions have
to be shown. The hardest, however, of all definitions to treat in
argument are those that employ terms about which, in the first
place, it is uncertain whether they are used in one sense or
several, and, further, whether they are used literally or
metaphorically by the definer. For because of their obscurity, it is
impossible to argue upon such terms; and because of the
impossibility of saying whether this obscurity is due to their being
used metaphorically, it is impossible to refute them.
  In general, it is safe to suppose that, whenever any problem
proves intractable, it either needs definition or else bears either
several senses, or a metaphorical sense, or it is not far removed from
the first principles; or else the reason is that we have yet to
discover in the first place just this-in which of the aforesaid
directions the source of our difficulty lies: when we have made this
clear, then obviously our business must be either to define or to
distinguish, or to supply the intermediate premisses: for it is
through these that the final conclusions are shown.
  It often happens that a difficulty is found in discussing or arguing
a given position because the definition has not been correctly
rendered: e.g. 'Has one thing one contrary or many?': here when the
term 'contraries' has been properly defined, it is easy to bring
people to see whether it is possible for the same thing to have
several contraries or not: in the same way also with other terms
requiring definition. It appears also in mathematics that the
difficulty in using a figure is sometimes due to a defect in
definition; e.g. in proving that the line which cuts the plane
parallel to one side divides similarly both the line which it cuts and
the area; whereas if the definition be given, the fact asserted
becomes immediately clear: for the areas have the same fraction
subtracted from them as have the sides: and this is the definition
of 'the same ratio'. The most primary of the elementary principles are
without exception very easy to show, if the definitions involved, e.g.
the nature of a line or of a circle, be laid down; only the
arguments that can be brought in regard to each of them are not
many, because there are not many intermediate steps. If, on the
other hand, the definition of the starting-points be not laid down, to
show them is difficult and may even prove quite impossible. The case
of the significance of verbal expressions is like that of these
mathematical conceptions.
  One may be sure then, whenever a position is hard to discuss, that
one or other of the aforesaid things has happened to it. Whenever,
on the other hand, it is a harder task to argue to the point
claimed, i.e. the premiss, than to the resulting position, a doubt may
arise whether such claims should be admitted or not: for if a man is
going to refuse to admit it and claim that you shall argue to it as
well, he will be giving the signal for a harder undertaking than was
originally proposed: if, on the other hand, he grants it, he will be
giving the original thesis credence on the strength of what is less
credible than itself. If, then, it is essential not to enhance the
difficulty of the problem, he had better grant it; if, on the other
hand, it be essential to reason through premisses that are better
assured, he had better refuse. In other words, in serious inquiry he
ought not to grant it, unless he be more sure about it than about
the conclusion; whereas in a dialectical exercise he may do so if he
is merely satisfied of its truth. Clearly, then, the circumstances
under which such admissions should be claimed are different for a mere
questioner and for a serious teacher.

                                 4

  As to the formulation, then, and arrangement of one's questions,
about enough has been said.
  With regard to the giving of answers, we must first define what is
the business of a good answerer, as of a good questioner. The business
of the questioner is so to develop the argument as to make the
answerer utter the most extrvagant paradoxes that necessarily follow
because of his position: while that of the answerer is to make it
appear that it is not he who is responsible for the absurdity or
paradox, but only his position: for one may, perhaps, distinguish
between the mistake of taking up a wrong position to start with, and
that of not maintaining it properly, when once taken up.

                                 5

  Inasmuch as no rules are laid down for those who argue for the
sake of training and of examination:-and the aim of those engaged in
teaching or learning is quite different from that of those engaged
in a competition; as is the latter from that of those who discuss
things together in the spirit of inquiry: for a learner should
always state what he thinks: for no one is even trying to teach him
what is false; whereas in a competition the business of the questioner
is to appear by all means to produce an effect upon the other, while
that of the answerer is to appear unaffected by him; on the other
hand, in an assembly of disputants discussing in the spirit not of a
competition but of an examination and inquiry, there are as yet no
articulate rules about what the answerer should aim at, and what
kind of things he should and should not grant for the correct or
incorrect defence of his position:-inasmuch, then, as we have no
tradition bequeathed to us by others, let us try to say something upon
the matter for ourselves.
  The thesis laid down by the answerer before facing the
questioner's argument is bound of necessity to be one that is either
generally accepted or generally rejected or else is neither: and
moreover is so accepted or rejected either absolutely or else with a
restriction, e.g. by some given person, by the speaker or by some
one else. The manner, however, of its acceptance or rejection,
whatever it be, makes no difference: for the right way to answer, i.e.
to admit or to refuse to admit what has been asked, will be the same
in either case. If, then, the statement laid down by the answerer be
generally rejected, the conclusion aimed at by the questioner is bound
to be one generally accepted, whereas if the former be generally
accepted, the latter is generally rejected: for the conclusion which
the questioner tries to draw is always the opposite of the statement
laid down. If, on the other hand, what is laid down is generally
neither rejected nor accepted, the conclusion will be of the same type
as well. Now since a man who reasons correctly demonstrates his
proposed conclusion from premisses that are more generally accepted,
and more familiar, it is clear that (1) where the view laid down by
him is one that generally is absolutely rejected, the answerer ought
not to grant either what is thus absolutely not accepted at all, or
what is accepted indeed, but accepted less generally than the
questioner's conclusion. For if the statement laid down by the
answerer be generally rejected, the conclusion aimed at by the
questioner will be one that is generally accepted, so that the
premisses secured by the questioner should all be views generally
accepted, and more generally accepted than his proposed conclusion, if
the less familiar is to be inferred through the more familiar.
Consequently, if any of the questions put to him be not of this
character, the answerer should not grant them. (2) If, on the other
hand, the statement laid down by the answerer be generally accepted
without qualification, clearly the conclusion sought by the questioner
will be one generally rejected without qualification. Accordingly, the
answerer should admit all views that are generally accepted and, of
those that are not generally accepted, all that are less generally
rejected than the conclusion sought by the questioner. For then he
will probably be thought to have argued sufficiently well. (3)
Likewise, too, if the statement laid down by the answerer be neither
rejected generally nor generally accepted; for then, too, anything
that appears to be true should be granted, and, of the views not
generally accepted, any that are more generally accepted than the
questioner's conclusion; for in that case the result will be that
the arguments will be more generally accepted. If, then, the view laid
down by the answerer be one that is generally accepted or rejected
without qualification, then the views that are accepted absolutely
must be taken as the standard of comparison: whereas if the view
laid down be one that is not generally accepted or rejected, but
only by the answerer, then the standard whereby the latter must
judge what is generally accepted or not, and must grant or refuse to
grant the point asked, is himself. If, again, the answerer be
defending some one else's opinion, then clearly it will be the
latter's judgement to which he must have regard in granting or denying
the various points. This is why those, too, who introduce other's
opinions, e.g. that 'good and evil are the same thing, as Heraclitus
says,' refuse to admit the impossibility of contraries belonging at
the same time to the same thing; not because they do not themselves
believe this, but because on Heraclitus' principles one has to say so.
The same thing is done also by those who take on the defence of one
another's positions; their aim being to speak as would the man who
stated the position.

                                 6

  It is clear, then, what the aims of the answerer should be,
whether the position he lays down be a view generally accepted without
qualification or accepted by some definite person. Now every
question asked is bound to involve some view that is either
generally held or generally rejected or neither, and is also bound
to be either relevant to the argument or irrelevant: if then it be a
view generally accepted and irrelevant, the answerer should grant it
and remark that it is the accepted view: if it be a view not generally
accepted and irrelevant, he should grant it but add a comment that
it is not generally accepted, in order to avoid the appearance of
being a simpleton. If it be relevant and also be generally accepted,
he should admit that it is the view generally accepted but say that it
lies too close to the original proposition, and that if it be
granted the problem proposed collapses. If what is claimed by the
questioner be relevant but too generally rejected, the answerer, while
admitting that if it be granted the conclusion sought follows,
should yet protest that the proposition is too absurd to be
admitted. Suppose, again, it be a view that is neither rejected
generally nor generally accepted, then, if it be irrelevant to the
argument, it may be granted without restriction; if, however, it be
relevant, the answerer should add the comment that, if it be
granted, the original problem collapses. For then the answerer will
not be held to be personally accountable for what happens to him, if
he grants the several points with his eyes open, and also the
questioner will be able to draw his inference, seeing that all the
premisses that are more generally accepted than the conclusion are
granted him. Those who try to draw an inference from premisses more
generally rejected than the conclusion clearly do not reason
correctly: hence, when men ask these things, they ought not to be
granted.

                                 7

  The questioner should be met in a like manner also in the case of
terms used obscurely, i.e. in several senses. For the answerer, if
he does not understand, is always permitted to say 'I do not
understand': he is not compelled to reply 'Yes' or 'No' to a
question which may mean different things. Clearly, then, in the
first place, if what is said be not clear, he ought not to hesitate to
say that he does not understand it; for often people encounter some
difficulty from assenting to questions that are not clearly put. If he
understands the question and yet it covers many senses, then supposing
what it says to be universally true or false, he should give it an
unqualified assent or denial: if, on the other hand, it be partly true
and partly false, he should add a comment that it bears different
senses, and also that in one it is true, in the other false: for if he
leave this distinction till later, it becomes uncertain whether
originally as well he perceived the ambiguity or not. If he does not
foresee the ambiguity, but assents to the question having in view
the one sense of the words, then, if the questioner takes it in the
other sense, he should say, 'That was not what I had in view when I
admitted it; I meant the other sense': for if a term or expression
covers more than one thing, it is easy to disagree. If, however, the
question is both clear and simple, he should answer either 'Yes' or
'No'.

                                 8

  A premiss in reasoning always either is one of the constituent
elements in the reasoning, or else goes to establish one of these:
(and you can always tell when it is secured in order to establish
something else by the fact of a number of similar questions being put:
for as a rule people secure their universal by means either of
induction or of likeness):-accordingly the particular propositions
should all be admitted, if they are true and generally held. On the
other hand, against the universal one should try to bring some
negative instance; for to bring the argument to a standstill without a
negative instance, either real or apparent, shows ill-temper. If,
then, a man refuses to grant the universal when supported by many
instances, although he has no negative instance to show, he
obviously shows ill-temper. If, moreover, he cannot even attempt a
counter-proof that it is not true, far more likely is he to be thought
ill-tempered-although even counter-proof is not enough: for we often
hear arguments that are contrary to common opinions, whose solution is
yet difficult, e.g. the argument of Zeno that it is impossible to move
or to traverse the stadium;-but still, this is no reason for
omitting to assert the opposites of these views. If, then, a man
refuses to admit the proposition without having either a negative
instance or some counter-argument to bring against it, clearly he is
ill-tempered: for ill-temper in argument consists in answering in ways
other than the above, so as to wreck the reasoning.

                                 9

  Before maintaining either a thesis or a definition the answerer
should try his hand at attacking it by himself; for clearly his
business is to oppose those positions from which questioners
demolish what he has laid down.
  He should beware of maintaining a hypothesis that is generally
rejected: and this it may be in two ways: for it may be one which
results in absurd statements, e.g. suppose any one were to say that
everything is in motion or that nothing is; and also there are all
those which only a bad character would choose, and which are
implicitly opposed to men's wishes, e.g. that pleasure is the good,
and that to do injustice is better than to suffer it. For people
then hate him, supposing him to maintain them not for the sake of
argument but because he really thinks them.

                                10

  Of all arguments that reason to a false conclusion the right
solution is to demolish the point on which the fallacy that occurs
depends: for the demolition of any random point is no solution, even
though the point demolished be false. For the argument may contain
many falsehoods, e.g. suppose some one to secure the premisses, 'He
who sits, writes' and 'Socrates is sitting': for from these it follows
that 'Socrates is writing'. Now we may demolish the proposition
'Socrates is sitting', and still be no nearer a solution of the
argument; it may be true that the point claimed is false; but it is
not on that that fallacy of the argument depends: for supposing that
any one should happen to be sitting and not writing, it would be
impossible in such a case to apply the same solution. Accordingly,
it is not this that needs to be demolished, but rather that 'He who
sits, writes': for he who sits does not always write. He, then, who
has demolished the point on which the fallacy depends, has given the
solution of the argument completely. Any one who knows that it is on
such and such a point that the argument depends, knows the solution of
it, just as in the case of a figure falsely drawn. For it is not
enough to object, even if the point demolished be a falsehood, but the
reason of the fallacy should also be proved: for then it would be
clear whether the man makes his objection with his eyes open or not.
  There are four possible ways of preventing a man from working his
argument to a conclusion. It can be done either by demolishing the
point on which the falsehood that comes about depends, or by stating
an objection directed against the questioner: for often when a
solution has not as a matter of fact been brought, yet the
questioner is rendered thereby unable to pursue the argument any
farther. Thirdly, one may object to the questions asked: for it may
happen that what the questioner wants does not follow from the
questions he has asked because he has asked them badly, whereas if
something additional be granted the conclusion comes about. If,
then, the questioner be unable to pursue his argument farther, the
objection would properly be directed against the questioner; if he can
do so, then it would be against his questions. The fourth and worst
kind of objection is that which is directed to the time allowed for
discussion: for some people bring objections of a kind which would
take longer to answer than the length of the discussion in hand.
  There are then, as we said, four ways of making objections: but of
them the first alone is a solution: the others are just hindrances and
stumbling-blocks to prevent the conclusions.

                                11

  Adverse criticism of an argument on its own merits, and of it when
presented in the form of questions, are two different things. For
often the failure to carry through the argument correctly in
discussion is due to the person questioned, because he will not
grant the steps of which a correct argument might have been made
against his position: for it is not in the power of the one side
only to effect properly a result that depends on both alike.
Accordingly it sometimes becomes necessary to attack the speaker and
not his position, when the answerer lies in wait for the points that
are contrary to the questioner and becomes abusive as well: when
people lose their tempers in this way, their argument becomes a
contest, not a discussion. Moreover, since arguments of this kind
are held not for the sake of instruction but for purposes of
practice and examination, clearly one has to reason not only to true
conclusions, but also to false ones, and not always through true
premisses, but sometimes through false as well. For often, when a true
proposition is put forward, the dialectician is compelled to
demolish it: and then false propositions have to be formulated.
Sometimes also when a false proposition is put forward, it has to be
demolished by means of false propositions: for it is possible for a
given man to believe what is not the fact more firmly than the
truth. Accordingly, if the argument be made to depend on something
that he holds, it will be easier to persuade or help him. He, however,
who would rightly convert any one to a different opinion should do
so in a dialectical and not in a contentious manner, just as a
geometrician should reason geometrically, whether his conclusion be
false or true: what kind of syllogisms are dialectical has already
been said. The principle that a man who hinders the common business is
a bad partner, clearly applies to an argument as well; for in
arguments as well there is a common aim in view, except with mere
contestants, for these cannot both reach the same goal; for more
than one cannot possibly win. It makes no difference whether he
effects this as answerer or as questioner: for both he who asks
contentious questions is a bad dialectician, and also he who in
answering fails to grant the obvious answer or to understand the point
of the questioner's inquiry. What has been said, then, makes it
clear that adverse criticism is not to be passed in a like strain upon
the argument on its own merits, and upon the questioner: for it may
very well be that the argument is bad, but that the questioner has
argued with the answerer in the best possible way: for when men lose
their tempers, it may perhaps be impossible to make one's inferences
straight-forwardly as one would wish: we have to do as we can.
  Inasmuch as it is indeterminate when people are claiming the
admission of contrary things, and when they are claiming what
originally they set out to prove-for often when they are talking by
themselves they say contrary things, and admit afterwards what they
have previously denied; for which reason they often assent, when
questioned, to contrary things and to what originally had to be
proved-the argument is sure to become vitiated. The responsibility,
however, for this rests with the answerer, because while refusing to
grant other points, he does grant points of that kind. It is, then,
clear that adverse criticism is not to be passed in a like manner upon
questioners and upon their arguments.
  In itself an argument is liable to five kinds of adverse criticism:
  (1) The first is when neither the proposed conclusion nor indeed any
conclusion at all is drawn from the questions asked, and when most, if
not all, of the premisses on which the conclusion rests are false or
generally rejected, when, moreover, neither any withdrawals nor
additions nor both together can bring the conclusions about.
  (2) The second is, supposing the reasoning, though constructed
from the premisses, and in the manner, described above, were to be
irrelevant to the original position.
  (3) The third is, supposing certain additions would bring an
inference about but yet these additions were to be weaker than those
that were put as questions and less generally held than the
conclusion.
  (4) Again, supposing certain withdrawals could effect the same:
for sometimes people secure more premisses than are necessary, so that
it is not through them that the inference comes about.
  (5) Moreover, suppose the premisses be less generally held and
less credible than the conclusion, or if, though true, they require
more trouble to prove than the proposed view.
  One must not claim that the reasoning to a proposed view shall in
every case equally be a view generally accepted and convincing: for it
is a direct result of the nature of things that some subjects of
inquiry shall be easier and some harder, so that if a man brings
people to accept his point from opinions that are as generally
received as the case admits, he has argued his case correctly.
Clearly, then, not even the argument itself is open to the same
adverse criticism when taken in relation to the proposed conclusion
and when taken by itself. For there is nothing to prevent the argument
being open to reproach in itself, and yet commendable in relation to
the proposed conclusion, or again, vice versa, being commendable in
itself, and yet open to reproach in relation to the proposed
conclusion, whenever there are many propositions both generally held
and also true whereby it could easily be proved. It is possible also
that an argument, even though brought to a conclusion, may sometimes
be worse than one which is not so concluded, whenever the premisses of
the former are silly, while its conclusion is not so; whereas the
latter, though requiring certain additions, requires only such as
are generally held and true, and moreover does not rest as an argument
on these additions. With those which bring about a true conclusion
by means of false premisses, it is not fair to find fault: for a false
conclusion must of necessity always be reached from a false premiss,
but a true conclusion may sometimes be drawn even from false
premisses; as is clear from the Analytics.
  Whenever by the argument stated something is demonstrated, but
that something is other than what is wanted and has no bearing
whatever on the conclusion, then no inference as to the latter can
be drawn from it: and if there appears to be, it will be a sophism,
not a proof. A philosopheme is a demonstrative inference: an
epichireme is a dialectical inference: a sophism is a contentious
inference: an aporeme is an inference that reasons dialectically to
a contradiction.
  If something were to be shown from premisses, both of which are
views generally accepted, but not accepted with like conviction, it
may very well be that the conclusion shown is something held more
strongly than either. If, on the other hand, general opinion be for
the one and neither for nor against the other, or if it be for the one
and against the other, then, if the pro and con be alike in the case
of the premisses, they will be alike for the conclusion also: if, on
the other hand, the one preponderates, the conclusion too will
follow suit.
  It is also a fault in reasoning when a man shows something through a
long chain of steps, when he might employ fewer steps and those
already included in his argument: suppose him to be showing (e.g.)
that one opinion is more properly so called than another, and
suppose him to make his postulates as follows: 'x-in-itself is more
fully x than anything else': 'there genuinely exists an object of
opinion in itself': therefore 'the object-of-opinion-in-itself is more
fully an object of opinion than the particular objects of opinion'.
Now 'a relative term is more fully itself when its correlate is more
fully itself': and 'there exists a genuine opinion-in-itself, which
will be "opinion" in a more accurate sense than the particular
opinions': and it has been postulated both that 'a genuine
opinion-in-itself exists', and that 'x-in-itself is more fully x
than anything else': therefore 'this will be opinion in a more
accurate sense'. Wherein lies the viciousness of the reasoning? Simply
in that it conceals the ground on which the argument depends.

                                12

  An argument is clear in one, and that the most ordinary, sense, if
it be so brought to a conclusion as to make no further questions
necessary: in another sense, and this is the type most usually
advanced, when the propositions secured are such as compel the
conclusion, and the argument is concluded through premisses that are
themselves conclusions: moreover, it is so also if some step is
omitted that generally is firmly accepted.
  An argument is called fallacious in four senses: (1) when it appears
to be brought to a conclusion, and is not really so-what is called
'contentious' reasoning: (2) when it comes to a conclusion but not
to the conclusion proposed-which happens principally in the case of
reductiones ad impossibile: (3) when it comes to the proposed
conclusion but not according to the mode of inquiry appropriate to the
case, as happens when a non-medical argument is taken to be a
medical one, or one which is not geometrical for a geometrical
argument, or one which is not dialectical for dialectical, whether the
result reached be true or false: (4) if the conclusion be reached
through false premisses: of this type the conclusion is sometimes
false, sometimes true: for while a false conclusion is always the
result of false premisses, a true conclusion may be drawn even from
premisses that are not true, as was said above as well.
  Fallacy in argument is due to a mistake of the arguer rather than of
the argument: yet it is not always the fault of the arguer either, but
only when he is not aware of it: for we often accept on its merits
in preference to many true ones an argument which demolishes some true
proposition if it does so from premisses as far as possible
generally accepted. For an argument of that kind does demonstrate
other things that are true: for one of the premisses laid down ought
never to be there at all, and this will then be demonstrated. If,
however, a true conclusion were to be reached through premisses that
are false and utterly childish, the argument is worse than many
arguments that lead to a false conclusion, though an argument which
leads to a false conclusion may also be of this type. Clearly then the
first thing to ask in regard to the argument in itself is, 'Has it a
conclusion?'; the second, 'Is the conclusion true or false?'; the
third, 'Of what kind of premisses does it consist?': for if the
latter, though false, be generally accepted, the argument is
dialectical, whereas if, though true, they be generally rejected, it
is bad: if they be both false and also entirely contrary to general
opinion, clearly it is bad, either altogether or else in relation to
the particular matter in hand.

                                13

  Of the ways in which a questioner may beg the original question
and also beg contraries the true account has been given in the
Analytics:' but an account on the level of general opinion must be
given now.
  People appear to beg their original question in five ways: the first
and most obvious being if any one begs the actual point requiring to
be shown: this is easily detected when put in so many words; but it is
more apt to escape detection in the case of different terms, or a term
and an expression, that mean the same thing. A second way occurs
whenever any one begs universally something which he has to
demonstrate in a particular case: suppose (e.g.) he were trying to
prove that the knowledge of contraries is one and were to claim that
the knowledge of opposites in general is one: for then he is generally
thought to be begging, along with a number of other things, that which
he ought to have shown by itself. A third way is if any one were to
beg in particular cases what he undertakes to show universally: e.g.
if he undertook to show that the knowledge of contraries is always
one, and begged it of certain pairs of contraries: for he also is
generally considered to be begging independently and by itself what,
together with a number of other things, he ought to have shown. Again,
a man begs the question if he begs his conclusion piecemeal: supposing
e.g. that he had to show that medicine is a science of what leads to
health and to disease, and were to claim first the one, then the
other; or, fifthly, if he were to beg the one or the other of a pair
of statements that necessarily involve one other; e.g. if he had to
show that the diagonal is incommensurable with the side, and were to
beg that the side is incommensurable with the diagonal.
  The ways in which people assume contraries are equal in number to
those in which they beg their original question. For it would
happen, firstly, if any one were to beg an opposite affirmation and
negation; secondly, if he were to beg the contrary terms of an
antithesis, e.g. that the same thing is good and evil; thirdly,
suppose any one were to claim something universally and then proceed
to beg its contradictory in some particular case, e.g. if having
secured that the knowledge of contraries is one, he were to claim that
the knowledge of what makes for health or for disease is different;
or, fourthly, suppose him, after postulating the latter view, to try
to secure universally the contradictory statement. Again, fifthly,
suppose a man begs the contrary of the conclusion which necessarily
comes about through the premisses laid down; and this would happen
suppose, even without begging the opposites in so many words, he
were to beg two premisses such that this contradictory statement
that is opposite to the first conclusion will follow from them. The
securing of contraries differs from begging the original question in
this way: in the latter case the mistake lies in regard to the
conclusion; for it is by a glance at the conclusion that we tell
that the original question has been begged: whereas contrary views lie
in the premisses, viz. in a certain relation which they bear to one
another.

                                14

  The best way to secure training and practice in arguments of this
kind is in the first place to get into the habit of converting the
arguments. For in this way we shall be better equipped for dealing
with the proposition stated, and after a few attempts we shall know
several arguments by heart. For by 'conversion' of an argument is
meant the taking the reverse of the conclusion together with the
remaining propositions asked and so demolishing one of those that were
conceded: for it follows necessarily that if the conclusion be untrue,
some one of the premisses is demolished, seeing that, given all the
premisses, the conclusion was bound to follow. Always, in dealing with
any proposition, be on the look-out for a line of argument both pro
and con: and on discovering it at once set about looking for the
solution of it: for in this way you will soon find that you have
trained yourself at the same time in both asking questions and
answering them. If we cannot find any one else to argue with, we
should argue with ourselves. Select, moreover, arguments relating to
the same thesis and range them side by side: for this produces a
plentiful supply of arguments for carrying a point by sheer force, and
in refutation also it is of great service, whenever one is well
stocked with arguments pro and con: for then you find yourself on your
guard against contrary statements to the one you wish to secure.
Moreover, as contributing to knowledge and to philosophic wisdom the
power of discerning and holding in one view the results of either of
two hypotheses is no mean instrument; for it then only remains to make
a right choice of one of them. For a task of this kind a certain
natural ability is required: in fact real natural ability just is
the power right to choose the true and shun the false. Men of
natural ability can do this; for by a right liking or disliking for
whatever is proposed to them they rightly select what is best.
  It is best to know by heart arguments upon those questions which are
of most frequent occurrence, and particularly in regard to those
propositions which are ultimate: for in discussing these answerers
frequently give up in despair. Moreover, get a good stock of
definitions: and have those of familiar and primary ideas at your
fingers' ends: for it is through these that reasonings are effected.
You should try, moreover, to master the heads under which other
arguments mostly tend to fall. For just as in geometry it is useful to
be practised in the elements, and in arithmetic to have the
multiplication table up to ten at one's fingers' ends-and indeed it
makes a great difference in one's knowledge of the multiples of
other numbers too-likewise also in arguments it is a great advantage
to be well up in regard to first principles, and to have a thorough
knowledge of premisses at the tip of one's tongue. For just as in a
person with a trained memory, a memory of things themselves is
immediately caused by the mere mention of their loci, so these
habits too will make a man readier in reasoning, because he has his
premisses classified before his mind's eye, each under its number.
It is better to commit to memory a premiss of general application than
an argument: for it is difficult to be even moderately ready with a
first principle, or hypothesis.
  Moreover, you should get into the habit of turning one argument into
several, and conceal your procedure as darkly as you can: this kind of
effect is best produced by keeping as far as possible away from topics
akin to the subject of the argument. This can be done with arguments
that are entirely universal, e.g. the statement that 'there cannot
be one knowledge of more than one thing': for that is the case with
both relative terms and contraries and co-ordinates.
  Records of discussions should be made in a universal form, even
though one has argued only some particular case: for this will
enable one to turn a single rule into several. A like rule applies
in Rhetoric as well to enthymemes. For yourself, however, you should
as far as possible avoid universalizing your reasonings. You should,
moreover, always examine arguments to see whether they rest on
principles of general application: for all particular arguments really
reason universally, as well, i.e. a particular demonstration always
contains a universal demonstration, because it is impossible to reason
at all without using universals.
  You should display your training in inductive reasoning against a
young man, in deductive against an expert. You should try, moreover,
to secure from those skilled in deduction their premisses, from
inductive reasoners their parallel cases; for this is the thing in
which they are respectively trained. In general, too, from your
exercises in argumentation you should try to carry away either a
syllogism on some subject or a refutation or a proposition or an
objection, or whether some one put his question properly or improperly
(whether it was yourself or some one else) and the point which made it
the one or the other. For this is what gives one ability, and the
whole object of training is to acquire ability, especially in regard
to propositions and objections. For it is the skilled propounder and
objector who is, speaking generally, a dialectician. To formulate a
proposition is to form a number of things into one-for the
conclusion to which the argument leads must be taken generally, as a
single thing-whereas to formulate an objection is to make one thing
into many; for the objector either distinguishes or demolishes, partly
granting, partly denying the statements proposed.
  Do not argue with every one, nor practise upon the man in the
street: for there are some people with whom any argument is bound to
degenerate. For against any one who is ready to try all means in order
to seem not to be beaten, it is indeed fair to try all means of
bringing about one's conclusion: but it is not good form. Wherefore
the best rule is, not lightly to engage with casual acquaintances,
or bad argument is sure to result. For you see how in practising
together people cannot refrain from contentious argument.
  It is best also to have ready-made arguments relating to those
questions in which a very small stock will furnish us with arguments
serviceable on a very large number of occasions. These are those
that are universal, and those in regard to which it is rather
difficult to produce points for ourselves from matters of everyday
experience.


                            THE END